Physical activity on prescription for children with obesity: a focus group study exploring experiences in paediatric healthcare.

Background: Insufficient physical activity is a growing public health concern and is closely linked to obesity in both adults and children. Swedish physical activity on prescription (PAP) is effective in increasing physical activity levels in adults, but knowledge about how PAP is used in paediatric healthcare is lacking. Therefore, this study aimed to explore experiences of working with PAP for children with obesity amongst paediatric staff and managers. Methods: Seven focus group discussions with 26 participants from paediatric outpatient clinics in western Sweden were conducted. Data were analysed both inductively and deductively, framed by the Normalization Process Theory's four core constructs: coherence, cognitive participation, collective action, and reflexive monitoring. Results: The PAP work for children with obesity was experienced to be about helping children to become physically active, and less about losing weight. Identified barriers for using PAP were the non-uniform nature of the work and a perceived lack of guidelines. Collaboration with physiotherapists and physical activity organisers outside the organisation was identified as an important facilitator. An important contextual factor for implementing PAP is the collaboration between paediatric clinics and physical activity organisers. In the transition between these stakeholders, maintaining a family-centred approach when working with PAP was experienced as challenging. Conclusions: PAP is a well-known intervention that is inconsistently used for children with obesity. The intervention should include a family-centred approach for this patient group. It also needs to align better with existing collaborations with other healthcare units as well as with new forms of collaboration with physical activity organisers in the community.

Cost-Effectiveness of Prolonged Physical Activity on Prescription in Previously Non-Complying Patients: Impact of Physical Activity Mediators.

In Sweden, physical activity on prescription (PAP) is used to support patients in increasing their levels of physical activity (PA). The role of healthcare professionals in supporting PA behavior change requires optimization in terms of knowledge, quality and organization. This study aims to evaluate the cost-effectiveness of support from a physiotherapist (PT) compared to continued PAP at a healthcare center (HCC) for patients who remained insufficiently active after 6-month PAP treatment at the HCC. The PT strategy was constituted by a higher follow-up frequency as well as by aerobic physical fitness tests. The analysis was based on an RCT with a three-year time horizon, including 190 patients aged 27-77 with metabolic risk factors. The cost per QALY for the PT strategy compared to the HCC strategy was USD 16,771 with a societal perspective (including individual PA expenses, production loss and time cost for exercise, as well as healthcare resource use) and USD 33,450 with a healthcare perspective (including only costs related to healthcare resource use). Assuming a willingness-to-pay of USD 57,000 for a QALY, the probability of cost-effectiveness for the PT strategy was 0.5 for the societal perspective and 0.6 for the healthcare perspective. Subgroup analyses on cost-effectiveness based on individual characteristics regarding enjoyment, expectations and confidence indicated potential in identifying cost-effective strategies based on mediating factors. However, this needs to be further explored. In conclusion, both PT and HCC interventions are similar from a cost-effectiveness perspective, indicating that both strategies are equally valuable in healthcare's range of treatments.

The effects of a 5-year physical activity on prescription (PAP) intervention in patients with metabolic risk factors.

BACKGROUND: Increased physical activity (PA) has positive effects on health and longevity. In Swedish healthcare, the physical activity on prescription (PAP) method reportedly increases patients' PA levels for up to 12 months, but long-term follow ups are lacking. As it remains difficult to maintain lifestyle changes, our aim was to evaluate adherence and clinical effects at a 5-year follow-up of PAP treatment in primary healthcare. METHODS: This longitudinal, prospective cohort study included 444 patients, (56% female), aged 27-85 years, with at least one metabolic risk factor. Participants were offered PAP by nurses or physiotherapists. The PAP intervention included an individualised dialogue, a PA recommendation by written prescription, and individually adjusted follow-up over 5 years, according to the Swedish PAP model. Patient PA level, metabolic risk factors, and health related quality of life (HRQoL) were measured at baseline and at the 6-month, 1.5-year, 2.5-year, 3.5-year, and 5-year follow-ups. Estimated latent growth curves were used to examine levels and rates of change in the outcomes. RESULTS: The study dropout rate was 52%, with 215 of 444 patients completing the 5-year follow-up. At follow-up, the mean PA level had increased by 730 MET-minutes per week or 3 hours of moderate-intensity PA/week when compared to baseline. During the 5-year intervention, we observed significant positive changes (p ≤ 0.05) in 9 of 11 metabolic risk factors and HRQoL parameters: body mass index, waist circumference, systolic and diastolic blood pressure, fasting plasma glucose, triglycerides, cholesterol, high-density lipoprotein, and mental component summary. CONCLUSION: This first evaluation of a 5-year PAP intervention in primary care demonstrated positive long-term (5 years) effects regarding PA level, metabolic health, and HRQoL. The recorded long-term adherence was ~50%, which is in line with medical treatment. Despite limitations, PAP can have long-term effects in an ordinary primary care setting.

[Physical activity in metabolic syndrome]. / Fysisk aktivitet kan förbättra faktorer i metabola syndromet.

The metabolic syndrome includes: abdominal obesity, insulin resistance, hypertension, and dyslipidemia in various combinations with an increased risk for developing cardiovascular disease, type 2 diabetes, and cancer. All components of the metabolic syndrome are positively affected by increased physical activity, while aerobic physical activity on a moderate to vigorous intensity level or a combination of aerobic and muscle strengthening physical activity are optimal. The physical activity should be individually adapted and in dialogue with the patient, and Physical activity on prescription can be used as a treatment method.

Implementation of physical activity on prescription for children with obesity in paediatric health care (IMPA): protocol for a feasibility and evaluation study using quantitative and qualitative methods.

BACKGROUND: Physical inactivity is a main cause of childhood obesity which tracks into adulthood obesity, making it important to address early in life. Physical activity on prescription (PAP) is an evidence-based intervention that has shown good effect on physical activity levels in adults, but has not been evaluated in children with obesity. This project aims to evaluate the prerequisites, determinants, and feasibility of implementing PAP adapted to children with obesity and to explore children's, parents', and healthcare providers' experiences of PAP. METHODS: In the first phase of the project, healthcare providers and managers from 26 paediatric clinics in Region Västra Götaland, Sweden, will be invited to participate in a web-based survey and a subset of this sample for a focus group study. Findings from these two data collections will form the basis for adaptation of PAP to the target group and context. In a second phase, this adapted PAP intervention will be evaluated in a clinical study in a sample of approximately 60 children with obesity (ISO-BMI > 30) between 6 and 12 years of age and one of their parents/legal guardians. Implementation process and clinical outcomes will be assessed pre- and post-intervention and at 8 and 12 months' follow-up. Implementation outcomes are the four core constructs of the Normalization Process Theory; coherence, cognitive participation, collective action, and reflexive monitoring; and appropriateness, acceptability, and feasibility of the PAP intervention. Additional implementation process outcomes are recruitment and attrition rates, intervention fidelity, dose, and adherence. Clinical outcomes are physical activity pattern, BMI, metabolic risk factors, health-related quality of life, sleep, and self-efficacy and motivation for physical activity. Lastly, we will explore the perspectives of children and parents in semi-structured interviews. Design and analysis of the included studies are guided by the Normalization Process Theory. DISCUSSION: This project will provide new knowledge regarding the feasibility of PAP for children with obesity and about whether and how an evidence-based intervention can be fitted and adapted to new contexts and populations. The results may inform a larger scale trial and future implementation and may enhance the role of PAP in the management of obesity in paediatric health care in Sweden. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04847271 , registered 14 April 2021.

Prerequisites for implementing physical activity on prescription for children with obesity in paediatric health care: A cross-sectional survey.

Background: Physical inactivity is a main driver of childhood obesity that tracks into adulthood, making it crucial to address early in life. Swedish physical activity on prescription (PAP) is an effective intervention for increasing physical activity levels in adults and is being implemented in primary care in Sweden. Before implementing PAP for children, both intervention effectiveness and implementation prerequisites need to be examined. Framed by the Normalization Process Theory (NPT) domains, this study aimed to investigate perceptions of PAP amongst paediatric staff and managers working with children with obesity, as well as acceptability, appropriateness, feasibility, and barriers and facilitators for implementing PAP in paediatric health care. Methods: Staff and managers in 28 paediatric outpatient clinics in western Sweden were surveyed using validated implementation instruments and open-ended questions. Data were analysed using Mann-Whitney U tests and Kruskal-Wallis tests. Qualitative data were categorised into NPT domains. Results: The survey response rate was 54% (125/229). Most respondents (82%) reported PAP to be familiar and many (56%) perceived it as a normal part of work; nurses and physiotherapists to a greater extent (p < 0.001). This was anticipated to increase in the future (82%), especially amongst those with the longest work experience (p = 0.012). Respondents reported seeing the potential value in their work with PAP (77%), being open to working in new ways to use PAP (94%), and having confidence in their colleagues' ability to use PAP (77%). Barriers and facilitators were found in all the NPT domains, mainly collective action and reflexive monitoring, where, for example, inadequacies of education, resources, and research on PAP for children were reported as barriers. Most respondents agreed that PAP was acceptable, appropriate, and feasible (71% to 88%). Conclusions: PAP is familiar and perceived as an acceptable, appropriate, and feasible intervention, and by many viewed as a normal part of clinical routines in paediatric outpatient clinics in western Sweden, especially by physiotherapists and nurses. Barriers and faciliators are mainly related to collective action and reflexive monitoring. The wide acceptance demonstrates receptiveness to PAP as an intervention to promote an active lifestyle for children with obesity.

Long-term effects of physical activity prescription after bariatric surgery: A randomized controlled trial.

PURPOSE: This study examined the effects of physical activity prescription (PAP) in patients after gastric bypass surgery. Patients' physical activity (PA) levels and outcomes were followed over their first postoperative year. METHODS: Patients slated for bariatric surgery were randomized to a control group (n = 64) (basic information about postoperative PA) or an intervention group (n = 57) (also received physical therapist-prescribed PAP). Outcome measures were self-reported PA/exercise and sedentary time; and weight, waist circumference, blood pressure, and blood lipids; recorded pre-operatively and at 2, 6, and 12 months postoperatively. Follow-ups were conducted by nurses/dieticians. Trial registration: "Research and Development in Sweden" number 107371. RESULTS: There were no differences between the groups except for higher level of PA (579 vs. 182 minutes/week) six months after surgery (p = .046) and a larger decrease in cholesterol (-24 vs. -8%) after a year (p = .017) in the intervention group. Patients in both groups lost considerable weight, had reduced waist circumference, and increased PA (p < .001). CONCLUSION: Although marked differences between groups were not observed over one year, the intervention group increased its PA 6-months postoperatively, but not at other time points. Whether long-term outcomes of PAP use are more robust with physical therapist participation across follow-ups warrants study.

Nonresponders of Physical Activity on Prescription (PAP) Can Increase Their Exercise Capacity with Enhanced Physiotherapist Support.

Swedish physical activity on prescription (PAP) is an evidence-based method to promote physical activity. However, few studies have investigated the effect of Swedish PAP on physical fitness, in which better cardiorespiratory fitness is associated with lower risks of all-cause mortality and diagnose-specific mortality. Direct measures of cardiorespiratory fitness, usually expressed as maximal oxygen uptake, are difficult to obtain. Hence, exercise capacity can be assessed from a submaximal cycle ergometer test, taking the linear relationship between heart rate, work rate, and oxygen uptake into account. The aim of this study was to evaluate exercise capacity in the long term, following PAP treatment with enhanced physiotherapist support in a nonresponding patient cohort. In total, 98 patients (48 women) with insufficient physical activity levels, with at least one component of the metabolic syndrome and nonresponding to a previous six-month PAP treatment, were randomized to PAP treatment with enhanced support from a physiotherapist and additional exercise capacity tests during a two-year period. A significant increase in exercise capacity was observed for the whole cohort at two-year follow-up (7.6 W, p ≤ 0.001), with a medium effect size (r = 0.34). Females (7.3 W, p = 0.025), males (8.0 W, p = 0.018) and patients ≥58 years old (7.7 W, p = 0.002) improved significantly, whereas a nonsignificant increase was observed for patients <58 years old (7.6 W, p = 0.085). Patients with insufficient physical activity levels who did not respond to a previous six-month PAP treatment can improve their exercise capacity following PAP treatment with enhanced support from a physiotherapist during a two-year period. Future studies should include larger cohorts with a control group to ensure valid estimations of exercise capacity and PAP.

Tailored physical activity on prescription with follow-ups improved motivation and physical activity levels. A qualitative study of a 5-year Swedish primary care intervention.

OBJECTIVE: To explore how physically inactive patients, with metabolic risk factors, experienced long term treatment with physical activity on prescription. DESIGN: Qualitative content analysis of individual interviews after strategical sampling of respondents. SETTING: Fifteen primary health care centres in Gothenburg, Sweden. SUBJECTS: Twenty physically inactive patients, with one or more metabolic syndrome components, 9 women, 11 men, mean age 58 years (25-73); 10 patients were responders and 10 non-responders to the intervention. MAIN OUTCOME MEASURES: Categories describing treatment effect and successful intervention. RESULTS: The interviews revealed three categories of effect. First, individual adjustments contributed to increased physical activity. Second, follow-up and support were valuable aids for prioritising and maintaining lifestyle changes. Third, motivation could be higher if patients make their own choices and experienced positive health effects. The overarching emerging theme was 'tailored physical activity on prescription with regular follow-ups can contribute to increased and maintained motivation and physical activity levels.'Conclusion Physical activity on prescription in a Swedish primary care setting was successful when the recommended physical activity and follow up was individually adapted. KEY POINTS Individually adapted physical activity on prescription gave insight to increase physical activity levels in a 5-year Swedish primary care intervention directed towards inactive patients with the metabolic syndrome Motivation increased for patients designing their own routines for physical activity. Experiences of positive health effects helped maintain or increase physical activity levels, and follow-up and support from healthcare professionals helped to prioritise life style changes.

Long-term physical activity on prescription intervention for patients with insufficient physical activity level-a randomized controlled trial.

BACKGROUND: Physical activity (PA) can be used to prevent and treat diseases. In Sweden, licensed healthcare professionals use PA on prescription (PAP) to support patients to increase their PA level. The aim of this randomized controlled trial was to evaluate a 2-year intervention of two different strategies of PAP treatment for patients with insufficient PA level, after a previous 6-month period of ordinary PAP treatment in a primary health care setting. METHODS: We included 190 patients, 27-77 years, physically inactive with metabolic risk factors where the patients were not responding to a previous 6-month PAP treatment with increased PA. The patients were randomized to either enhanced support from a physiotherapist (PT group) or continued ordinary PAP treatment at the health care centre (HCC group). The PAP treatment included an individualized dialogue; an individually dosed PA recommendation, including a written prescription; and a structured follow-up. In addition to PAP, the PT group received aerobic fitness tests and more frequent scheduled follow-ups. The patient PA level, metabolic health, and health-related quality of life (HRQOL) were measured at baseline and at 1- and 2-year follow-ups. RESULTS: At the 2-year follow-up, 62.9% of the PT group and 50.8% of the HCC group had increased their PA level and 31.4% vs. 38.5% achieved ≥ 150 min of moderate-intensity PA/week (difference between groups n.s.). Over 2 years, both groups displayed increased high-density lipoproteins (HDL) (p = 0.004 vs. baseline), increased mental health status (MCS) (p = 0.036), and reduced body mass index (BMI) (p = 0.001), with no difference between groups. CONCLUSION: During long-term PAP interventions, the PA level, metabolic health, and HRQOL increased in patients at metabolic risk without significant differences between groups. The results indicate to be independent of any changes in pharmacological treatment. We demonstrated that the PAP treatment was feasible in ordinary primary care. Both the patients and the healthcare system benefitted from the improvement in metabolic risk factors. Future studies should elucidate effective long-term PAP-treatment strategies. TRIAL REGISTRATION: ClinicalTrials.gov NCT03012516 . Registered on 30 December 2016-retrospectively registered.

What is the time cost of exercise? Cost of time spent on exercise in a primary health care intervention to increase physical activity.

BACKGROUND: In health care interventions aimed at increased physical activity, the individual's time spent on exercise is a substantial input. Time costs should therefore be considered in cost-effectiveness analyses. The aim of this study was to estimate the cost of time spent on exercise among 333 primary health care patients with metabolic risk factors receiving physical activity on prescription. METHODS: Based on a theoretical framework, a yardstick was constructed with experience of work (representing claim of salary as compensation) as the lower anchor-point, and experience of leisure activity forgone due to extended exercise time (no claim) as the higher anchor-point. Using this yardstick experience of exercise can be valued. Another yardstick was constructed with experience of cleaning at home in combination with willingness to pay for cleaning as the lowest anchor-point. RESULTS: The estimated costs of exercise time were between 14 and 37% of net wages, with physical activity level being the most important factor in determining the cost. Among sedentary individuals, the time cost was 21-51% of net wages while among individuals performing regular exercise it was 2-10%. When estimating the cost of time spent on exercise in a cost-effectiveness analysis, experience of exercise, work, leisure activity forgone, and cleaning at home (or other household work that may be relevant to purchase) should be measured. The individual's willingness to pay for cleaning at home and their net salary should also be measured. CONCLUSIONS: When using a single valuation of cost of time spent on exercise in health care interventions, for employed participants 15-30% of net salary should be used. Among unemployed individuals, lower cost estimation should be applied. Better precision in cost estimations can be achieved if participants are stratified by physical activity levels.Trial registration The study was conducted as a survey of existing clinical physical activity on prescription work, and was approved by the Regional Ethical Review Board in Gothenburg, Sweden (ref: 678-14).

Which patients benefit from physical activity on prescription (PAP)? A prospective observational analysis of factors that predict increased physical activity.

BACKGROUND: There is robust evidence that regular physical activity (PA) has positive health effects. However, the best PA methods and the most important correlates for promoting PA remain unclear. Physical activity on prescription (PAP) aims to increase the patient's motivation for and level of PA. This study investigated possible predictive baseline correlates associated with changes in the PA level over a 6-month period of PAP treatment in order to identify the primary care patients most likely to benefit from a PAP intervention. METHODS: The study included 444 patients with metabolic risk factors who were aged 27 to 85 years and physically inactive. The patients received PAP treatment that included individual counseling plus an individually-tailored PA recommendation with a written prescription and individualised structured follow-up for 6 months. Eight baseline correlates of PA were analysed against the PA level at the 6-month follow-up in a predictor analysis. RESULTS: Five baseline correlates predicted the PA level at the 6-month follow-up: self-efficacy expectations for changing PA; the patient's preparedness and confidence regarding readiness to change PA; a BMI <  30; and a positive valued physical health. The proportion of patients increasing the PA level and achieving a PA level that was in accordance with public health recommendations was higher with a positive valued baseline correlate. The odds of achieving the recommended PA level increased substantially when 2 to 4 predictive correlates were present. PA levels increased to a greater extent among patients with low PA at baseline than patients with high PA at baseline, especially in combination with 2 to 4 positively-valued correlates (87-95% vs. 62-75%). CONCLUSIONS: This study identified potential predictive correlates of an increased PA level after a 6-month PAP intervention. This contributes to our understanding of PAP and could help individualise PAP support. The proportion of patients with the lowest PA level at baseline increased their PA level in a higher extent (84%) and thus may benefit the most from PAP. These results have clinical implications for behavioural change in those patients having the greatest health gains by increasing their PA level. TRIAL REGISTRATION: ClinicalTrials.gov ; NCT03586011 . Retrospectively registered on July 17, 2018.

Physical activity on prescription in accordance with the Swedish model increases physical activity: a systematic review.

OBJECTIVES: This study investigates the effects of the core elements of the Swedish model for physical activity on prescription (PAP) by evaluating studies that compared adults who received PAP with adults who did not receive PAP. All participants were adults identified by a healthcare professional as in need of increased physical activity. Primary outcome was level of physical activity. DESIGN: Systematic review. ELIGIBILITY CRITERIA: (1) Published 1999. (2) Systematic review, randomised controlled trial (RCT), non-RCT or case series (for adverse events). (3) ≥12 weeks' follow-up. (4) Performed in the Nordic countries. (5) Presented in English, Swedish, Norwegian or Danish. DATA SOURCES: Systematic searches in PubMed, Embase, the Cochrane Library, AMED, CINAHL and SweMed+ in September 2017. Included articles were evaluated using checklists to determine risk of bias. RESULTS: Nine relevant articles were included: seven RCTs, one cohort study and one case series. Primary outcome was reported in seven articles from six studies (five RCTs, one cohort study, 642 participants). Positive results were reported from three of the five RCTs and from the cohort study. No study reported any negative results. Swedish PAP probably results in an increased level of physical activity (GRADE⊕⊕⊕Ο). CONCLUSIONS: Although the number of the reviewed articles was relatively modest, this systematic review shows that PAP in accordance with the Swedish model probably increases the level of physical activity. As a model for exercise prescription, Swedish PAP may be considered as part of regular healthcare to increase physical activity in patients.

Physical Activity on Prescription (PAP), in patients with metabolic risk factors. A 6-month follow-up study in primary health care.

There is strong evidence that inadequate physical activity (PA) leads to an increased risk of lifestyle-related diseases and premature mortality. Physical activity on prescription (PAP) is a method to increase the level of PA of patients in primary care, but needs further evaluation. The aim of this observational study was to explore the association between PAP-treatment and the PA level of patients with metabolic risk factors and the relationship between changes in the PA level and health outcomes at the 6 month follow-up. This study included 444 patients in primary care, aged 27-85 years (56% females), who were physically inactive with at least one component of metabolic syndrome. The PAP-treatment model included: individualized dialogue concerning PA, prescribed PA, and a structured follow-up. A total of 368 patients (83%) completed the 6 months of follow-up. Of these patients, 73% increased their PA level and 42% moved from an inadequate PA level to sufficient, according to public health recommendations. There were significant improvements (p≤ 0.05) in the following metabolic risk factors: body mass index, waist circumference, systolic blood pressure, fasting plasma glucose, cholesterol, and low density lipoprotein. There were also significant improvements regarding health-related quality of life, assessed by the Short Form 36, in: general health, vitality, social function, mental health, role limitation-physical/emotional, mental component summary, and physical component summary. Regression analysis showed a significant association between changes in the PA level and health outcomes. During the first 6-month period, the caregiver provided PAP support 1-2 times. This study indicates that an individual-based model of PAP-treatment has the potential to change people's PA behavior with improved metabolic risk factors and self-reported quality of life at the 6 month follow-up. Thus, PAP seems to be feasible in a clinical primary care practice, with minimum effort from healthcare professionals.

Physical activity and exercise lower blood pressure in individuals with hypertension: narrative review of 27 RCTs.

Regular physical activity (PA) reduces the blood pressure (BP) of individuals with hypertension. The present review analysed the scientific evidence for the BP lowering effect of aerobic PA in 27 randomised controlled studies on individuals with hypertension, and shows that regular medium-to-high-intensity aerobic activity reduces the BP by a mean of 11/5 mm Hg (level of evidence, 3+). In addition, three randomised controlled trials (RCTs) on isometric (static) activity showed a BP reduction of similar magnitude in hypertensives; dynamic resistance training may show less effect, as shown in five available RCTs (level of evidence 2+). As both the prevalence of hypertension and physical inactivity are high and increasing in today's society, PA has a great role to play as a single (when indicated) or additive treatment for hypertension. Furthermore, as competitive athletes are getting older, it can be expected that more athletes at different competitive levels will have hypertension. Certain considerations must be applied regarding evaluation and treatment of hypertension in athletes. Eligibility for competitive sports may be affected if target organ damage (TOD) is present; however, an athlete with well-controlled BP, having no additional risk factors or TOD, is eligible for all sports.

[Aerobic physical activity lowers blood pressure in hypertension]. / Aerob fysisk aktivitet sänker blodtrycket vid hypertoni.

Hypertension is one of the most important modifiable risk factors for cardiovascular morbidity and mortality. Physical inactivity plays a role in the development of (essential) hypertension. Increased physical activity may decrease the blood pressure in hypertensive individuals with 12/5 mm Hg (evidence grade +++ according to GRADE). A moderate/vigorous-intensity aerobic physical activity, at least 3 x 40-60 minutes/week, for 8 weeks, has the strongest evidence (evidence grade +++). Isometric (static) training may also decrease the blood pressure significantly (evidence grade ++).

Sensing of formaldehyde using a distributed feedback interband cascade laser emitting around 3493 nm.

We have demonstrated sensing of formaldehyde (H(2)CO) using a room-temperature distributed feedback interband cascade laser (ICL) emitting around 3493 nm. The ICL has been characterized and proved to be very suitable for tunable laser spectroscopy (TLS). The H(2)CO TLS spectra were recorded in direct absorption mode and showed excellent agreement with the Pacific Northwest National Laboratory database. The measurements reported here were taken from a series of measurements of a mixture of H(2)CO in air obtained by vaporizing a solution also containing methanol and formic acid. We obtained a resolution limit better than 1 ppm × m assuming a relative absorption of 10(-3).

Methodology for detection of carbon monoxide in hot, humid media by telecommunication distributed feedback laser-based tunable diode laser absorption spectrometry.

Detection of carbon monoxide (CO) in combustion gases by tunable diode laser spectrometry is often hampered by spectral interferences from H2O and CO2. A methodology for assessment of CO in hot, humid media using telecommunication distributed feedback lasers is presented. By addressing the R14 line at 6395.4 cm(-1), and by using a dual-species-fitting technique that incorporates the fitting of both a previously measured water background reference spectrum and a 2f-wavelength modulation lineshape function, percent-level concentrations of CO can be detected in media with tens of percent of water (c(H2O)≤40%) at T≤1000 °C with an accuracy of a few percent by the use of a single reference water spectrum for background correction.

Faraday modulation spectrometry of nitric oxide addressing its electronic X2Π - A2Σ+ band: I. Theory.

We give a simple two-transition model of Faraday modulation spectrometry (FAMOS) addressing the electronic X(2)Π(ν('') = 0) - A(2)Σ(+)(ν(') = 0) band in nitric oxide. The model is given in terms of the integrated line strength, S, and first Fourier coefficients for the magnetic-field-modulated dispersive line shape function. Although the two states addressed respond differently to the magnetic field (they adhere to the dissimilar Hund coupling cases), it is shown that the technique shares some properties with FAMOS when rotational-vibrational Q-transitions are targeted: the line shapes have a similar form and the signal strength has an analogous magnetic field and pressure dependence. The differences are that the maximum signal appears for larger magnetic field amplitudes and pressures, ∼1500 G and ∼200 Torr, respectively.

Faraday modulation spectrometry of nitric oxide addressing its electronic X2Π - A2Σ+ band: II. Experiment.

A first demonstration of Faraday modulation spectrometry (FAMOS) of nitric oxide (NO) addressing its strong electronic X(2)Π(ν″ = 0) - A(2)Σ(+)(ν(') = 0) band is presented. The instrumentation was constructed around a fully diode-laser-based laser system producing mW powers of ultraviolet light targeting the overlapping Q(22)(21/2) and R(12)Q(21/2) transitions at ∼226.6 nm. The work verifies a new two-transition model of FAMOS addressing the electronic transitions in NO given in an accompanying work. Although the experimental instrumentation could address neither the parameter space of the theory nor the optimum conditions, the line shapes and the pressure dependence could be verified under low-field conditions. NO could be detected down to a partial pressure of 13 µTorr, roughly corresponding to 10 ppb·m for an atmospheric pressure sample, which demonstrates the feasibility of FAMOS for sensitive detection of NO addressing its strong electronic band.