Recent Cannabis Use and Accelerometer-Measured Physical Activity and Sedentary Behavior Among Young-to-Midlife Adults: An Analysis of the National Health and Nutrition Examination Survey from 2011 to 2014.

Introduction: Cannabis use has been associated with reduced physical activity and increased sedentary behavior in adolescents. In adults, however, there is no conclusive evidence of such an association, and existing studies have primarily relied on self-reported activity measures. As cannabis use increases globally, a deeper understanding of its relationship with activity levels may inform clinical counseling and guidelines. This study investigated the association between recent cannabis use and accelerometer-measured activity. Methods: Data were obtained from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2014. We included adults in the United States who responded to a cannabis questionnaire and had at least 4 days of activity data from an ActiGraph GT3X+ accelerometer, which comprised participants from 18 to 59 years. The primary exposure was any self-reported cannabis use in the past 30 days. The primary outcome was daily sedentary time and secondary outcomes were daily light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA). Analyses were performed with multivariable quasi-Poisson regression models. Results: Of 4666 included adults, 658 (14.1%) reported recent cannabis use. After covariate adjustment, recent cannabis use was not associated with daily sedentary time (adjusted incidence rate ratio [aIRR] 0.99, 95% confidence interval [CI]: 0.98-1.01) or daily MVPA time (aIRR 1.01, 95% CI: 0.98-1.04). Daily LPA time was 4% greater with recent cannabis use (aIRR 1.04, 95% CI: 1.01-1.06). Conclusion: Recent cannabis use in young to midlife adults was not associated with accelerometer-measured sedentary or MVPA time, but it was associated with a marginal increase in LPA time of unclear clinical significance. Our findings provide evidence against existing concerns that cannabis use independently promotes sedentary behavior and decreases physical activity. Future prospective studies are needed to determine if these findings generalize to specific populations using cannabis including chronic pain patients.

Preoperative depression and outcomes after metabolic and bariatric surgery: A systematic narrative review.

Preoperative depression is prevalent among patients undergoing metabolic and bariatric surgery (MBS) and is a potentially modifiable risk factor. However, the impact of preoperative depression on MBS outcomes has not been systematically reviewed. A search of MEDLINE, Embase, Cochrane, and PsychINFO (inception to June 2023) was conducted for studies reporting associations between preoperative depression and any clinical or patient-reported outcomes after MBS. Eighteen studies (5 prospective and 13 retrospective) reporting on 5933 participants were included. Most participants underwent gastric bypass or sleeve gastrectomy. Meta-analyses were not conducted due to heterogeneity in reported outcomes; findings were instead synthesized using a narrative and tabular approach. Across 13 studies (n = 3390) the associations between preoperative depression and weight loss outcomes at 6-72 months were mixed overall. This may be related to differences in cohort characteristics, outcome definitions, and instruments used to measure depression. A small number of studies reported that preoperative depression was associated with lower quality of life, worse acute pain, and more perioperative complications after surgery. Most of the included studies were deemed to be at high risk of bias, resulting in low or very low certainty of evidence according to the Risk of Bias In Non-randomized Studies - of Exposure (ROBINS-E) tool. While the impact of preoperative depression on weight loss after MBS remains unclear, there is early evidence that depression has negative consequences on other patient-important outcomes. Adequately powered studies using more sophisticated statistical methods are needed to accurately estimate these associations.

The independent and combined impact of moral injury and moral distress on post-traumatic stress disorder symptoms among healthcare workers during the COVID-19 pandemic.

Background: Healthcare workers (HCWs) across the globe have reported symptoms of Post-Traumatic Stress Disorder (PTSD) during the COVID-19 pandemic. Moral Injury (MI) has been associated with PTSD in military populations, but is not well studied in healthcare contexts. Moral Distress (MD), a related concept, may enhance understandings of MI and its relation to PTSD among HCWs. This study examined the independent and combined impact of MI and MD on PTSD symptoms in Canadian HCWs during the pandemic.Methods: HCWs participated in an online survey between February and December 2021, with questions regarding sociodemographics, mental health and trauma history (e.g. MI, MD, PTSD, dissociation, depression, anxiety, stress, childhood adversity). Structural equation modelling was used to analyze the independent and combined impact of MI and MD on PTSD symptoms (including dissociation) among the sample when controlling for sex, age, depression, anxiety, stress, and childhood adversity.Results: A structural equation model independently regressing both MI and MD onto PTSD accounted for 74.4% of the variance in PTSD symptoms. Here, MI was strongly and significantly associated with PTSD symptoms (ß = .412, p < .0001) to a higher degree than MD (ß = .187, p < .0001), after controlling for age, sex, depression, anxiety, stress and childhood adversity. A model regressing a combined MD and MI construct onto PTSD predicted approximately 87% of the variance in PTSD symptoms (r2 = .87, p < .0001), with MD/MI strongly and significantly associated with PTSD (ß = .813, p < .0001), after controlling for age, sex, depression, anxiety, stress, and childhood adversity.Conclusion: Our results support a relation between MI and PTSD among HCWs and suggest that a combined MD and MI construct is most strongly associated with PTSD symptoms. Further research is needed better understand the mechanisms through which MD/MI are associated with PTSD.

MI and MD were each independently associated with PTSD symptoms (including dissociation), when controlling for sex, age, childhood adversity, depression, anxiety and stress.Combining both MI and MD constructs into a single latent variable accounted for the greatest proportion of variance explained in PTSD symptoms among HCWs during the COVID-19 pandemic.Results suggest that expanding the construct of MI to include team and systemic organisational MD may be appropriate in the healthcare context.

Canadian respiratory therapists who considered leaving their clinical position experienced elevated moral distress and adverse psychological and functional outcomes during the COVID-19 pandemic. / Détresse morale et conséquences psychologiques et fonctionnelles négatives chez les thérapeutes respiratoires canadiens ayant envisagé de quitter leur poste clinique pendant la pandémie de COVID-19.

INTRODUCTION: Respiratory therapists (RTs) faced morally distressing situations throughout the COVID-19 pandemic, including working with limited resources and facilitating video calls for families of dying patients. Moral distress is associated with a host of adverse psychological and functional outcomes (e.g. depression, anxiety, symptoms of posttraumatic stress disorder [PTSD] and functional impairment) and consideration of position departure. The purpose of this study was to understand the impact of moral distress and its associated psychological and functional outcomes on consideration to leave a clinical position among Canadian RTs during the COVID-19 pandemic. METHODS: Canadian RTs (N = 213) completed an online survey between February and June 2021. Basic demographic information (e.g. age, sex, gender) and psychometrically validated measures of moral distress, depression, anxiety, stress, PTSD, dissociation, functional impairment, resilience and adverse childhood experiences were collected. RESULTS: One in four RTs reported considering leaving their position. RTs considering leaving reported elevated levels of moral distress and adverse psychological and functional outcomes compared to RTs not considering leaving. Over half (54.5%) of those considering leaving scored above the cut-off for potential diagnosis of PTSD. Previous consideration to leave a position and having left a position in the past each significantly increased the odds of currently considering leaving, along with system-related moral distress and symptoms of PTSD, but the contribution of these latter factors was small. CONCLUSIONS: Canadian RTs considering leaving their position reported elevated levels of distress and adverse psychological and functional outcomes, yet these individual-level factors appear unlikely to be the primary factors underlying RTs' consideration to leave, because their effects were small. Further research is required to identify broader, organizational factors that may contribute to consideration of position departure among Canadian RTs.

Coping, Supports and Moral Injury: Spiritual Well-Being and Organizational Support Are Associated with Reduced Moral Injury in Canadian Healthcare Providers during the COVID-19 Pandemic.

Healthcare providers (HCPs) have described the onset of shame- and trust-violation-related moral injuries (MI) throughout the COVID-19 pandemic. Previous research suggests that HCPs may turn to various coping methods and supports, such as spirituality/religiosity, substance use, friends/family or organizational support, to manage workplace stress. It remains unknown, however, if similar coping methods and supports are associated with MI among this population. We explored associations between MI (including the shame and trust-violation presentations individually) and coping methods and supports. Canadian HCPs completed an online survey about their mental health and experiences during the COVID-19 pandemic, including demographic indices (e.g., sex, age, mental health history) and measures of MI, organizational support, social support, spiritual well-being, self-compassion, alcohol use, cannabis use and childhood adversity. Three hierarchical multiple linear regressions were conducted to assess the associations between coping methods/supports and (i) MI, (ii) shame-related MI and (iii) trust-violation-related MI, when controlling for age, mental health history and childhood adversity. One hundred and seventy-six (N = 176) HCPs were included in the data analysis. Spiritual well-being and organizational support were each significantly associated with reduced total MI (p's < 0.001), shame-related MI (p = 0.03 and p = 0.02, respectively) and trust-violation-related MI (p's < 0.001). Notably, comparison of the standardized beta coefficients suggests that the association between trust-violation-related MI and both spiritual well-being and organizational support was more than twice as great as the associations between these variables and shame-related MI, emphasizing the importance of these supports and the trust-violation outcomes particularly. Mental health history (p = 0.02) and self-compassion (p = 0.01) were additionally related to shame-related MI only. Our findings indicate that heightened levels of spiritual well-being and organizational support were associated with reduced MI among HCPs during the COVID-19 pandemic. Rather than placing sole responsibility for mental health outcomes on HCPs individually, organizations can instead play a significant role in mitigating MI among staff by implementing evidence-informed organizational policies and interventions and by considering how supports for spiritual well-being may be implemented into existing models of care where relevant for employees.

Characterizing the mental health and functioning of Canadian respiratory therapists during the COVID-19 pandemic.

Introduction: Healthcare professionals (HCPs) appear to be at increased risk for negative psychological outcomes [e.g. depression, anxiety, post-traumatic stress disorder (PTSD), moral distress] and associated impacts on functioning throughout the COVID-19 pandemic. HCPs working on designated COVID-19 units may be further impacted than their colleagues not on these units given added demands of patient care and risk of contracting COVID-19. Little is known, however, about the mental health and functioning of specific professional groups beyond nurses and physicians, including respiratory therapists (RTs), over the course of the pandemic. Accordingly, the purpose of the present study was to characterize the mental health and functioning of Canadian RTs and compare profiles between RTs working on and off designated COVID-19 units.Methods: Canadian RTs completed an online survey between February and June 2021, including demographic information (e.g. age, sex, gender,) and measures of depression, anxiety, stress, PTSD, moral distress and functional impairment. Descriptive statistics, correlation analyses and between-groups comparisons were conducted to characterize RTs and compare profiles between those on and off COVID-19 units.Results: Two hundred and eighteen (N = 218) RTs participated in this study. The estimated response rate was relatively low (6.2%) Approximately half of the sample endorsed clinically relevant symptoms of depression (52%), anxiety (51%) and stress (54%) and one in three (33%) screened positively for potential PTSD. All symptoms correlated positively with functional impairment (p's < .05). RTs working on COVID-19 units reported significantly greater patient-related moral distress compared to those not on these units (p < .05).Conclusion: Moral distress and symptoms of depression, anxiety, stress and PTSD were prevalent among Canadian RTs and were associated with functional impacts. These results must be interpreted with caution given a low response rate, yet raise concern regarding the long-term impacts of pandemic service among RTs.

Research on RTs' mental health prior to and during the COVID-19 pandemic is scant, especially in comparison to other HCPs.RTs in the present study reported experiencing moral distress and clinically significant symptoms of depression, anxiety and PTSD, with associated functional impairment.One in three RTs screened positive for likely PTSD on the PCL-5.There is a need to provide RTs with adequate mental health supports and to understand the long-term impacts of pandemic service among RTs.

The Hidden Crisis: Understanding Potentially Morally Injurious Events Experienced by Healthcare Providers during COVID-19 in Canada.

BACKGROUND: Healthcare providers (HCPs) may be at elevated risk for moral injury due to increased exposure to potentially morally injurious events (PMIEs) throughout the COVID-19 pandemic. Identifying PMIEs experienced during the COVID-19 pandemic is a critical first step for understanding moral injury in HCPs. Accordingly, the purpose of the present study was to gain a deeper understanding of the work-related PMIEs experienced by HCPs in Canada during the pandemic. METHODS: Canadian HCPs completed an online survey between February and December 2021 about mental health and functioning, including demographics and the Moral Injury Outcome Scale (MIOS). We conducted a qualitative thematic analysis of PMIEs described extemporaneously by HCPs in the open-text field of the MIOS. RESULTS: One-hundred and twenty-four (N = 124) HCPs were included in analysis. Eight PMIE-related themes were identified, comprising patients dying alone; provision of futile care; professional opinion being ignored; witnessing patient harm; bullying, violence and divided opinions; resources and personal protective equipment; increased workload and decreased staffing; and conflicting values. CONCLUSIONS: Understanding broad categories of PMIES experienced by Canadian HCPs during the COVID-19 pandemic provides an opportunity to enhance cultural competency surrounding their experiences which will aid the development of targeted prevention and intervention approaches.

A Qualitative Approach to Understanding Canadian Healthcare Workers' Use of Coping Strategies during the COVID-19 Pandemic.

Throughout the COVID-19 pandemic, healthcare workers (HCWs) have been exposed to highly stressful situations, including increased workloads and exposure to mortality, thus posing a risk for adverse psychological outcomes, including acute stress, moral injury, and depression or anxiety symptoms. Although several reports have sought to identify the types of coping strategies used by HCWs over the course of the pandemic (e.g., physical activity, religion/spirituality, meditation, and alcohol), it remains unclear which factors may influence HCWs' choice of these coping strategies. Accordingly, using a qualitative approach, the purpose of the present study was to gain a deeper understanding of the factors influencing HCWs' choice of coping strategies during the COVID-19 pandemic in Canada. Fifty-one HCWs participated in virtual, semi-structured interviews between February and June 2021. Interview transcripts were analysed through an inductive thematic approach, yielding two primary themes. First, HCWs described an ongoing shift in their approach to coping depending on their mental "bandwidth", ranging from "quick fix" to more "intentional effort" strategies to engage in proactive strategies to improve mental health. Second, many HCWs identified various barriers to desired coping strategies during the pandemic, including the preponderance of pandemic- and other circumstantial-related barriers. The findings from this study offer a unique understanding of the factors influencing HCWs' choice of coping strategies under novel and increased stress. This knowledge will be central to developing appropriate forms of support and resources to equip HCWs throughout and after the pandemic period, and in mitigating the potential adverse mental health impacts of this period of prolonged stress and potential trauma.

Size matters! Investigating the effects of model size on anatomy learning.

Three-dimensional (3D) scanning and printing technology has allowed for the production of anatomical replicas at virtually any size. But what size optimizes the educational potential of 3D printing models? This study systematically investigates the effect of model size on nominal anatomy learning. The study population of 380 undergraduate students, without prior anatomical knowledge, were randomized to learn from two of four bone models (either vertebra and pelvic bone [os coxae], or scapula and sphenoid bone), each model 3D printed at 50%, 100%, 200%, and either 300% or 400% of normal size. Participants were then tested on nominal anatomy recall on the respective bone specimens. Mental rotation ability and working memory were also assessed, and opinions regarding learning with the various models were solicited. The diameter of the rotational bounding sphere for the object ("longest diameter") had a small, but significant effect on test score (F(2,707) = 17.15, p < 0.05, R2  = 0.046). Participants who studied from models with a longest diameter greater than 10 cm scored significantly better than those who used models less than 10 cm, with the exception of the scapula model, on which performance was equivalent across all sizes. These results suggest that models with a longest diameter beyond 10 cm are unlikely to incur a greater size-related benefit in learning nominal anatomy. Qualitative feedback suggests that there also appear to be inherent features of bones besides longest diameter that facilitate learning.

Childhood nephrotic syndrome and the clinical profile of thromboembolism: a systematic review and meta-analysis.

Nephrotic syndrome (NS) is a common kidney disease of childhood, affecting 2-7 children per 100,000. A potentially life-threatening complication affecting children with NS is thromboembolism (TE). However, there remains a paucity of information regarding the burden of TE and its associated risk factors in this population. A systematic review was performed on observational studies examining TE events in children with NS, published in Medline, Embase, CINAHL, and CENTRAL, until May 2021. Meta-analyses were separately conducted on the prevalence of TE within articles exclusively studying children with congenital NS and among articles including all forms of NS. Out of 13,626 articles, 22 were included (14,290 children). The pooled prevalence of symptomatic TE among articles including patients with all forms of NS was 3.60% (95% CI 1.95-5.63), which increased to 8.70% (95% CI 5.11-12.96) in articles with exclusively congenital NS patients. Children with steroid-resistant NS were at a higher risk of TE compared to steroid-sensitive children (OR 4.40, 95% CI 1.34-15.59, p = 0.013). Focal segmental glomerulosclerosis was the most common histology present in patients with TE (51.2%). Children diagnosed with NS have a significant risk of TE, particularly in patients with congenital NS and steroid resistance. IMPACT: The prevalence of symptomatic thromboembolic (TE) events in children with nephrotic syndrome (NS) was 3.60% (95% CI 1.95-5.63), which increased more than two-fold in children with congenital NS to 8.70% (95% CI 5.11-12.96). Potential risk factors for TE events in this population include congenital forms of NS and steroid resistance. This review provides a better estimate of the prevalence of TE in children with NS, while identifying potentially higher-risk populations who may benefit from TE screening and thromboprophylaxis.

Potential Circumstances Associated With Moral Injury and Moral Distress in Healthcare Workers and Public Safety Personnel Across the Globe During COVID-19: A Scoping Review.

Healthcare workers (HCWs) and public safety personnel (PSP) across the globe have continued to face ethically and morally challenging situations during the COVID-19 pandemic that increase their risk for the development of moral distress (MD) and moral injury (MI). To date, however, the global circumstances that confer risk for MD and MI in these cohorts have not been systematically explored, nor have the unique circumstances that may exist across countries been explored. Here, we sought to identify and compare, across the globe, potentially morally injurious or distressful events (PMIDEs) in HCWs and PSP during the COVID-19 pandemic. A scoping review was conducted to identify and synthesize global knowledge on PMIDEs in HCWs and select PSP. Six databases were searched, including MEDLINE, EMBASE, Web of Science, PsychInfo, CINAHL, and Global Health. A total of 1,412 articles were retrieved, of which 57 articles were included in this review. These articles collectively described the experiences of samples from 19 different countries, which were comprised almost exclusively of HCWs. Given the lack of PSP data, the following results should not be generalized to PSP populations without further research. Using qualitative content analysis, six themes describing circumstances associated with PMIDEs were identified: (1) Risk of contracting or transmitting COVID-19; (2) Inability to work on the frontlines; (3) Provision of suboptimal care; (4) Care prioritization and resource allocation; (5) Perceived lack of support and unfair treatment by their organization; and (6) Stigma, discrimination, and abuse. HCWs described a range of emotions related to these PMIDEs, including anxiety, fear, guilt, shame, burnout, anger, and helplessness. Most PMIDE themes appeared to be shared globally, particularly the 'Risk of contracting or transmitting COVID-19' and the 'Perceived lack of support and unfair treatment by their organization.' Articles included within the theme of 'Stigma, discrimination, and abuse' represented the smallest global distribution of all PMIDE themes. Overall, the present review provides insight into PMIDEs encountered by HCWs across the globe during COVID-19. Further research is required to differentiate the experience of PSP from HCWs, and to explore the impact of social and cultural factors on the experience of MD and MI.

Representation of women on editorial boards of ophthalmology journals: protocol for a cross-sectional study.

INTRODUCTION: There is a notable under-representation of women in leadership positions in ophthalmology despite the increasing number of women as ophthalmologists. Gender inequality in editorial boards of ophthalmology journals has not been investigated on a global scale. This study will aim to evaluate the representation of women as editorial board members in ophthalmology journals across different regions, journal subspecialties and impact factors. METHODS AND ANALYSIS: This will be a cross-sectional study describing the gender composition of editorial boards in ophthalmology journals globally. Ulrich's Periodicals Directory and SCImago Journal & Country Rank will be used to comprehensively identify journals indexed with the keyword, 'ophthalmology'. All journals with active websites and lists of editorial boards will be included. Journals will be categorised according to the World Bank's 2021 classification of countries by income and region, and classified into ophthalmology subspecialties based on publication scope. Impact factors will be obtained from Journal Citation Reports. The gender and academic degrees of each editorial board member will be determined based on journal profiles, institutional websites or name query feature on an online interface. The research impact of each editorial board member will be ascertained from the author records on Web of Science. The gender proportion will be presented for all journals combined, and then for journals grouped by regions, subspecialties and impact factors. Editorial board member characteristics including academic degrees and research productivity measures will be compared between men and women. These comparisons will be made using the χ2 test for categorical variables and the independent samples t-test for continuous variables. ETHICS AND DISSEMINATION: This study did not require research ethics approval given the use of publicly available data and lack of human subjects. The results will be presented at scientific meetings and published in peer-reviewed journals.

Use of rituximab in paediatric nephrology.

Rituximab is a chimeric monoclonal antibody capable of depleting B cell populations by targeting the CD20 antigen expressed on the cell surface. Its use in oncology, initially in B cell lymphoma and post-transplant lymphoproliferative disorders, predates its current utility in various fields of medicine wherein it has become one of the safest and most effective antibody-based therapies. It was subsequently found to be effective for rheumatological conditions such as rheumatoid arthritis and antineutrophil cytoplasmic antibody-associated vasculitis. Over the past decade, rituximab has generated a lot of interest in nephrology and has become an emerging or accepted therapy for multiple renal conditions, including systemic lupus erythematosus, lupus nephritis, vasculitis, nephrotic syndrome and in different scenarios before and after kidney transplantation. This review outlines its current use in paediatric nephrology practice, focusing on the knowledge required for general paediatricians who may be caring for children prescribed this medication and reviewing them on a shared care basis.

Antidepressant-like effect of dehydrozingerone from Zingiber officinale by elevating monoamines in brain: in silico and in vivo studies.

BACKGROUND: Dehydrozingerone (DHZ) is an active ingredient of Zingiber officinale and structural half analogue of curcumin. In the present study, DHZ was evaluated for monoamine oxidase (MAO) inhibitory activity in silico and antidepressant activity in vivo. METHOD: The binding affinity of DHZ with MAO-A (PDB ID: 2Z5Y) was assessed using Schrodinger's Maestro followed by free energy calculation, pharmacokinetic property prediction using Qikprop and Molecular dynamics simulation using Desmond. In vivo antidepressant activity of DHZ was evaluated on C57 BL/6 male mice using Escilatopram as the standard antidepressant. Open field test (OFT), forced swimming test (FST) and tail suspension test (TST) were used to evaluate the antidepressant effect of the drugs on days 1 and 7. Following the behavioural study, neurotransmitters (noradrenaline, dopamine and serotonin) were estimated using liquid chromatography-mass spectrometry. RESULTS: DHZ demonstrated a greater binding affinity for the MAO-A enzyme compared to moclobemide in silico. Immobility in TST and FST were significantly (p < 0.05) reduced in vivo with 100mg/kg DHZ as compared to respective controls. DHZ treatment was more effective 1 h post treatment compared to vehicle control. A significant increase in levels of neurotransmitters was observed in mice brain homogenate in response to DHZ treatment, reassuring its antidepressant-like potential. CONCLUSION: DHZ demonstrated MAO-A inhibition in silico, and the increased neurotransmitter levels in the brain in vivo were associated with an antidepressant-like effect.

Theoretical and experimental studies on hydrogen migration in dissociative ionization of the methanol monocation to molecular ions H3 + and H2O.

The dissociative ionization processes of the methanol monocation CH3OH+ to H3 + + CHO and H2O+ + CH2 are studied by ab initio method, and hydrogen migration processes are confirmed in these two dissociation processes. Due to the positive charge assignment in dissociation processes, the fragmentation pathways of CH3OH+ to H3 + CHO+ and CH3OH+ to H2O + CH2 + are also calculated. The calculation results show that a neutral H2 moiety in the methanol monocation CH3OH+ is the origin of the formation of H3 +, and the ejection of fragment ions H3 + and H2O+ is more difficult than CHO+ and CH2 + respectively. Experimentally, by using a dc-slice imaging technique under an 800 nm femtosecond laser field, the velocity distributions of fragment ions H3 +, CHO+, CH2 +, and H2O+ are calculated from their corresponding sliced images. The presence of low-velocity components of these four fragment ions confirms that the formation of these ions is not from the Coulomb explosion of the methanol dication. Hence, the four hydrogen migration pathways from the methanol monocation CH3OH+ to H3 + + CHO, CHO+ + H3, H2O+ + CH2, and CH2 + + H2O are securely confirmed. It can be observed in the time-of-flight mass spectrum of ionization and dissociation of methanol that the ion yields of fragment ions H3 + and H2O+ are lower than CHO+ and CH2 + respectively, which is consistent with the theoretical results according to which dissociation from the methanol monocation to H3 + and H2O+ is more difficult than CHO+ and CH2 + respectively.

BrCl+ elimination from Coulomb explosion of 1,2-bromochloroethane induced by intense femtosecond laser fields.

By using a dc-slice imaging technique, photodissociation of 1,2-C2H4BrCl was investigated at 800 nm looking for heteronuclear unimolecular ion elimination of BrCl+ in an 80 fs laser field. The occurrence of fragment ion BrCl+ in the mass spectrum verified the existence of a unimolecular decomposition channel of BrCl+ in this experiment. The relative quantum yield of the BrCl+ channel was measured to be 0.8%. By processing and analyzing the velocity and angular distributions obtained from the corresponding sliced images of BrCl+ and its partner ion C2H4 +, we concluded that BrCl+ came from Coulomb explosion of the 1,2-bromochloroethane dication 1,2-C2H4BrCl2+. With the aid of quantum chemical calculations at the M06-2X/def2-TZVP level, the potential energy surface for BrCl+ detachment from 1,2-C2H4BrCl2+ has been examined in detail. According to the ab initio calculations, two transition state structures tended to correlate with the reactant 1,2-C2H4BrCl2+ and the products BrCl+ + C2H4 +. In this entire dissociation process, the C-Br and C-Cl bond lengths were observed to elongate asymmetrically, that is, the C-Br chemical bond broke firstly, and subsequently a new Br-Cl chemical bond started to emerge while the C-Cl bond continued to exist for a while. Hence, an asynchronous concerted elimination mechanism was favored for BrCl+ detachment.