The ecological suitability area of Cirsium lineare (Thunb.) Sch.-Bip. under future climate change in China based on MaxEnt modeling.

Many kinds of medicinal ingredients occur in Cirsium lineare that have good clinical efficacy, conferring on this species its high medicinal development value. However, with a rapidly changing global climate, it is increasingly imperative to study the factors affecting the habitat distribution and survival of species. We predicted the current and future distribution areas of suitable habitats for C. lineare, analyzed the importance of environmental variables in influencing habitat shifts, and described the alterations to suitable habitats of C. lineare in different periods (modern, 2050s, and 2070s) and scenarios (RCP2.6, RCP4.5, and RCP8.5). The results show that, under the current climate, the total suitable area of C. lineare is about 2,220,900 km2, of which the highly suitable portion amounts to ca. 292,600 km2. The minimum temperature of the coldest month, annual precipitation, and mean daily temperature range are the chief environmental variables affecting the distribution of habitat for C. lineare. In the same period, with rising greenhouse gas emission concentrations, the total suitable area will increase. In general, under future climate change, the suitable habitat for C. lineare will gradually migrate to the west and north, and its total suitable area will also expand. The results of this experiment can be used for the conservation and management of the wild resources of C. lineare. We can choose suitable growth areas to protect the medicinal resources of C. lineare through in situ conservation and artificial breeding.

The unusual quadruple bonding of nitrogen in ThN.

Nitrogen has five valence electrons and can form a maximum of three shared electron-pair bonds to complete its octet, which suggests that its maximum bond order is three. With a joint anion photoelectron spectroscopy and quantum chemistry investigation, we report herein that nitrogen presents a quadruple bonding interaction with thorium in ThN. The quadruple Th≣N bond consists of two electron-sharing Th-N π bonds formed between the Th-6dxz/6dyz and N 2px/2py orbitals, one dative Th←N σ bond and one weak Th←N σ bonding interaction formed between Th-6dz2 and N 2s/2pz orbitals. The ThC molecule has also been investigated and proven to have a similar bonding pattern as ThN. Nonetheless, due to one singly occupied σ-bond, ThC is assigned a bond order of 3.5. Moreover, ThC has a longer bond length as well as a lower vibrational frequency in comparison with ThN.

Correlation Study of the Spin-Orbit State-Resolved Scattering of Al(2P) in Oxidation Reaction and Nonreactive Collision.

Spin-orbit coupling plays an important role in chemical reactivity, especially in reactions that require the change of electron spin states. However, it is difficult to measure and analyze the reaction dynamics between spin-orbit splitting states, particularly for splitting states with a small energy difference. In this study, we find that nonreactive scattering of spin-orbit splitting states can provide complementary information that is overlooked in chemical reaction studies. Here, the oxidation reactivities of spin-orbit Al(2P1/2,3/2) states with small energy difference of 112 cm-1 are clearly distinguished in the high rotational AlO(v = 0 and 1, N) products at low collision energy of 507 cm-1 using a laser ablation crossed-beam and time-sliced ion velocity mapping technique, in conjunction with state-selected nonreactive scattering studies. For both the AlO(v = 0 and 1) channels, the spin-orbit relative reactivity σ3/2/σ1/2 increases with the increase of rotational level N of AlO products. However, for AlO(v = 0), the reactivity of the Al(2P3/2) excited state is consistently lower than that of the Al(2P1/2) ground state, whereas for AlO(v = 1), the reactivity of Al(2P3/2) is higher than that of Al(2P1/2) at a higher rotational state. The relative reactivity of spin-orbit split Al(2P) states at different scattering angles shows a more pronounced enhancement of forward scattering relative to side and backward scattering for Al(2P3/2) when a higher rotationally excited AlO is produced. Nonreactive scattering studies of Al(2P) suggest that the Al(2P3/2) state is deexcited to the ground Al(2P1/2) state at the sideways and backward scattering directions, and the deexcitation is supposed to reduce the reactivity of the excited Al(2P3/2) at the corresponding direction.

Association between Interactions among ACE Gene Polymorphisms and Essential Hypertension in Patients in the Hefei Region, Anhui, China.

Objective: Essential hypertension (EH) is a common cardiovascular disease that endangers human health. Its pathogenesis is complex and has not been fully elucidated. We explore the association between EH and interactions among polymorphisms of the angiotensin converting enzyme (ACE) gene in the Hefei region, Anhui, China. Methods: A total of 500 participants (400 hypertensive and 100 normotensive) were included in this study. The polymorphisms were detected via improved multiple ligase detection reaction (iMLDR). To improve the accuracy of prediction, multifactor dimensionality reduction (MDR) was used to analyze the overall effect of interactions among seven loci on the incidence of EH. Results: The frequencies of polymorphisms in the ACE genes rs12709426, rs4291, rs4309, rs4331, rs4343, rs4459609, and rs4461142 in the EH group were not statistically significantly different from those in the control group. We also found that the single nucleotide polymorphism (SNP) rs12709426 only had a homozygous AA genotype and no polymorphisms. There were no differences in the frequency of genetic polymorphisms between the EH and control groups. The best model explaining the EH group was the combined effect of ACE genes rs4291, rs4309, and rs4461142. Conclusion: There is an interaction effect among ACE gene loci in EH patients in Hefei region, Anhui, China. Also, the ACE gene SNP rs12709426 only has a homozygous AA genotype and does not show an association with EH.

Development of a tongue image-based machine learning tool for the diagnosis of gastric cancer: a prospective multicentre clinical cohort study.

Background: Tongue images (the colour, size and shape of the tongue and the colour, thickness and moisture content of the tongue coating), reflecting the health state of the whole body according to the theory of traditional Chinese medicine (TCM), have been widely used in China for thousands of years. Herein, we investigated the value of tongue images and the tongue coating microbiome in the diagnosis of gastric cancer (GC). Methods: From May 2020 to January 2021, we simultaneously collected tongue images and tongue coating samples from 328 patients with GC (all newly diagnosed with GC) and 304 non-gastric cancer (NGC) participants in China, and 16 S rDNA was used to characterize the microbiome of the tongue coating samples. Then, artificial intelligence (AI) deep learning models were established to evaluate the value of tongue images and the tongue coating microbiome in the diagnosis of GC. Considering that tongue imaging is more convenient and economical as a diagnostic tool, we further conducted a prospective multicentre clinical study from May 2020 to March 2022 in China and recruited 937 patients with GC and 1911 participants with NGC from 10 centres across China to further evaluate the role of tongue images in the diagnosis of GC. Moreover, we verified this approach in another independent external validation cohort that included 294 patients with GC and 521 participants with NGC from 7 centres. This study is registered at ClinicalTrials.gov, NCT01090362. Findings: For the first time, we found that both tongue images and the tongue coating microbiome can be used as tools for the diagnosis of GC, and the area under the curve (AUC) value of the tongue image-based diagnostic model was 0.89. The AUC values of the tongue coating microbiome-based model reached 0.94 using genus data and 0.95 using species data. The results of the prospective multicentre clinical study showed that the AUC values of the three tongue image-based models for GCs reached 0.88-0.92 in the internal verification and 0.83-0.88 in the independent external verification, which were significantly superior to the combination of eight blood biomarkers. Interpretation: Our results suggest that tongue images can be used as a stable method for GC diagnosis and are significantly superior to conventional blood biomarkers. The three kinds of tongue image-based AI deep learning diagnostic models that we developed can be used to adequately distinguish patients with GC from participants with NGC, even early GC and precancerous lesions, such as atrophic gastritis (AG). Funding: The National Key R&D Program of China (2021YFA0910100), Program of Zhejiang Provincial TCM Sci-tech Plan (2018ZY006), Medical Science and Technology Project of Zhejiang Province (2022KY114, WKJ-ZJ-2104), Zhejiang Provincial Research Center for Upper Gastrointestinal Tract Cancer (JBZX-202006), Natural Science Foundation of Zhejiang Province (HDMY22H160008), Science and Technology Projects of Zhejiang Province (2019C03049), National Natural Science Foundation of China (82074245, 81973634, 82204828), and Chinese Postdoctoral Science Foundation (2022M713203).

The additional nitrogen atom breaks the uranyl structure: a combined photoelectron spectroscopy and theoretical study of NUO2.

We report a joint photoelectron spectroscopic and relativistic quantum chemistry study on gaseous NUO2-. The electron affinity (EA) of the neutral NUO2 molecule is reported for the first time with a value of 2.602(28) eV. The U-O and U-N stretching vibrational modes for the ground state and the first excited state are observed for NUO2. The geometric and electronic structures of both the anions and the corresponding neutrals are investigated by relativistic quantum chemistry calculations to interpret the photoelectron spectra and to provide insights into the nature of the chemical bonding. Both the ground state of the anion and neutral are calculated to be planar structures with C2v symmetry. Unlike the "T"-shape structure of UO3 which has a quasi-linear O-U-O angle, both the ground-state geometries of the anion and neutral have O-U-O bond angles of around 90°. The significant contraction of the O-U-O bond angle indicates the strong interaction between the U and N atoms compared with the "additional" oxygen in UO3. The chemical bonding calculation indicates that multiple bonding of U(VI) can occur in NUO2- and NUO2, and the UVI-N bond is significantly more covalent than the U-O bond. The current experimental and theoretical results reveal the difference between the U-N and U-O bond in the unified molecular system, and expand our understanding of the bonding capacities of actinide elements with the nitrogen atom.

Effects of Ziyin Qianyang Formula on Renal Fibrosis through the TGF-ß1/Smads Signaling Pathway in Spontaneously Hypertensive Rats.

Objective: The aim of the study is to explore the effects and mechanisms of action of Ziyin Qianyang Formula (ZYQYF) on renal fibrosis in spontaneously hypertensive rats (SHRs). Methods: Forty SHRs were randomly divided into a model group, Ziyin Qianyang Formula regular-dose and high-dose groups (ZYQYF-R, 20 g/kg; ZYQYF-H, 40 g/kg), and a western medicine group (enalapril 10 mg/kg), and 10 Sprague-Dawley rats were selected as the normal group. The rats received continuous gavage administration for 6 weeks and systolic blood pressure (SBP) measurements were obtained every fortnight. The serum levels of urea, serum creatinine (sCr), and uric acid (UA) were measured; the pathological morphology and collagen content of the kidneys were observed by hematoxylin-eosin (HE) and Masson staining; and the serum Ang II level was measured by an enzyme-linked immunosorbent assay (ELISA). Transforming growth factor (TGF)-ß1, Smad-2, Smad-3, and Smad-7 protein and mRNA expressions in kidney tissues was evaluated by western blotting and reverse transcription-polymerase chain reaction. Results: The ZYQYF-H group showed significantly a lower renal weight and renal weight/body weight than the model group. The enalapril and ZYQYF-H groups showed significantly lower SBP than other groups after 6 weeks of administration. The ZYQYF-H group showed better improvement than the ZYQYF-R and enalapril groups in glomerular and tubular morphology and better reductions in inflammatory cell infiltration and collagen volumetric fraction. The ZYQYF-H group also showed better reductions in serum UA and Ang II levels; collagen-I, collagen-III, and p-Smad2/Smad-2 protein expression; and Smad-2 mRNA expression and a better increase in Smad-7 protein and mRNA expression than the enalapril group. Besides, the degree of renal function and fibrosis improvement was positively correlated with the dose of ZYQYF. Conclusion: ZYQYF can significantly reduce SHR blood pressure, protect renal function and structure, and improve renal fibrosis by regulating Smad proteins through TGF-ß1.

The past and future of transient receptor potential: A scientometric analysis.

BACKGROUND: Thermoreceptors include TRPV1 and TRPM8. TRPV1 and TRPM8 are TRP channels. TRP ion channels are widely expressed in many different tissues and cell types, and are involved in different physiological processes. Research on the structure and basic physiological functions of TRPV1 is relatively perfect, and the relationship between the pathogenesis of other members of the TRP family and specific diseases and TRPV1 remains to be explored in depth. METHODS: Articles regarding TRP were culled from the Web of Science Core Collection, and knowledge maps were generated using the CiteSpace software. RESULTS: In total, 19,862 articles were included. The number of published articles on this topic has rapidly increased since 2000, with more than 1000 articles published per year by 2020. MAKOTO TOMINAGA was the author with the most articles. The countries with the most articles were the United States and China. However, the number of articles in the U.S. was 3 times that in China. The organizations that publish the most articles are Harvard University in the US and Seoul Natl University in South Korea. TRP and the pathogenesis of diseases, such as neuropathy and stroke, are hotspots of current research. CONCLUSION: To our knowledge, this is the first study to provide an overview of the literature on TRP. Research on TRPs is developing rapidly.

Probing the electronic structure and Au-C bonding in AuC2nH (n = 4-7) using photoelectron imaging spectroscopy and quantum chemical calculations.

We report a combined experimental and theoretical study on the structures and chemical bonding of AuC2nH (n = 4-7) using photoelectron imaging and quantum chemical calculations. All the ground states of anions and neutral AuC2nH have a linear geometry. The electron affinities (EAs) are measured to be 2.063(5), 2.157(5), 2.220(5), and 2.267(5) eV for AuC2nH, n = 4-7, respectively. The photoelectron imaging data of AuC8H- and AuC10H- reveal major vibrational progressions in the Au-C stretching modes. The ground state stretching frequencies of the titled neutral molecules are 226, 193, 177, and 128 cm-1, respectively. By comparing the experimental ß value and theoretical molecular orbital analysis, we confirm that the CAM-B3LYP method is more suitable for describing the properties of such unsaturated long chains organogold clusters. The experimental and CAM-B3LYP methods give a big picture of the trend in EAs of AuC2nH. This shows that the EA value becomes larger with an increase in the carbon chain length, and it also shows a slow increment for larger n. The NRT analysis shows that the change of the Au-C bond order is not obvious as the number of carbon atoms increases, and the covalent character dominates the Au-C chemical bonds in these neutral species. The current study provides a wealth of electronic structure information about long-chain AuC2nH- (n = 4-7) and their corresponding neutral counterparts.

Establishing and validating a spotted tongue recognition and extraction model based on multiscale convolutional neural network / 数字中医药（英文）

@#Objective In tongue diagnosis, the location, color, and distribution of spots can be used to speculate on the viscera and severity of the heat evil. This work focuses on the image analysis method of artificial intelligence (AI) to study the spotted tongue recognition of traditional Chinese medicine (TCM). Methods A model of spotted tongue recognition and extraction is designed, which is based on the principle of image deep learning and instance segmentation. This model includes multiscale feature map generation, region proposal searching, and target region recognition. Firstly, deep convolution network is used to build multiscale low- and high-abstraction feature maps after which, target candidate box generation algorithm and selection strategy are used to select high-quality target candidate regions. Finally, classification network is used for classifying target regions and calculating target region pixels. As a result, the region segmentation of spotted tongue is obtained. Under non-standard illumination conditions, various tongue images were taken by mobile phones, and experiments were conducted. Results The spotted tongue recognition achieved an area under curve (AUC) of 92.40%, an accuracy of 84.30% with a sensitivity of 88.20%, a specificity of 94.19%, a recall of 88.20%, a regional pixel accuracy index pixel accuracy (PA) of 73.00%, a mean pixel accuracy (mPA) of 73.00%, an intersection over union (IoU) of 60.00%, and a mean intersection over union (mIoU) of 56.00%. Conclusion The results of the study verify that the model is suitable for the application of the TCM tongue diagnosis system. Spotted tongue recognition via multiscale convolutional neural network (CNN) would help to improve spot classification and the accurate extraction of pixels of spot area as well as provide a practical method for intelligent tongue diagnosis of TCM.

Global trends and performances of Mediterranean diet: A bibliometric analysis in CiteSpace.

BACKGROUND: The Mediterranean diet (MD) is an ancient eating habit that is believed to contribute to a healthy lifestyle. Unsurprisingly, research on the MD is growing rapidly as people pay more attention to health preservation and prevention, treatment and rehabilitation of chronic diseases. Previous reviews focused more on the effects of MD on a particular disease which has enhanced its significance in the medicine field. However, few studies have attempted to provide a comprehensive summary and analysis of this topic. This study evaluates the global research trends of scientific outputs related to MD from multiple perspectives, using a bibliometric analysis and visualization tool (CiteSpace software) to scientifically analyze the knowledge from the literature. METHODS: The core collection database of Web of Science was used to retrieve the bibliographic records related to MD from 1984 to March 30, 2021. CiteSpace was used to generate and analyze visual representations of the complex data input, including number of publications, research performances in journals, authors, institutions, countries and co-occurrence networks of keywords and co-citation references. RESULTS: Overall, the number of MD publications has shown a significant upward trend since 2012. Nutrients and American Journal of Clinical Nutrition contained the most articles related to MD, indicating that they were important platforms for related research. Martinez-gonzalez Ma and Estruch Ramon are the authors with the highest number of publications related to MD, and it is noteworthy that these 2 authors have close cooperation in this field. The countries with the most publications are Spain and the United States, and the institutions with the most publications are Univ Navarra, Inst Salud Carlos III. The main research disciplines are "Mediterranean diet," "risk," "cardiovascular disease," "adherence," "obesity," "coronary heart disease," "diet," "health," "physical activity" and "risk factor". Estruch R's 2013 study on cerebrovascular disease and Tricopoulou A's 2003 mortality study were cited 881 cases for 437 times, respectively, showing the importance of these 2 articles in this field. CONCLUSION: The current global trends of MD research as well as people's increasing awareness of healthcare and healthy lifestyle imply that MD research is expected to become increasingly popular with further breakthroughs.

A combined photoelectron-imaging spectroscopic and theoretical investigation on the electronic structure of the VO2H anion.

The electronic structure and vibrational spectrum of the VO2H anion are explored by combining photoelectron imaging spectroscopy and density functional theoretical (DFT) calculations. The electron affinity (EA) of VO2H is determined to be 1.304 ± 0.030 eV from the vibrationally resolved photoelectron spectrum acquired at 1.52 eV (814 nm). The anisotropy parameter (ß) for the EA defined peak is measured to be 1.63 ± 0.10, indicating that it is the 17a' (4s orbital of the vanadium atom) electron attachment leading to the formation of the ground state of the VO2H anion. The vibrational fundamentals ν 1, ν 3, ν 4 and ν 5 are obtained for the neutral ground state. Experimental assignments are confirmed by energies from electronic structure calculations and Franck-Condon (FC) spectral simulations. These simulations support assigning the anion ground state as the results obtained from the B3LYP method. In addition, the molecular orbitals and bonding involved in the anionic VO2H cluster are also examined based on the present theoretical calculations.

Probing the Hydrogen Bonding in Microsolvated Clusters of Au1,2-(Solv)n (Solv = C2H5OH, n-C3H7OH; n = 1-3 for Au-; n =1 for Au2-).

The microsolvation of gold anions in different alcohol solvents is demonstrated by the combination of anion photoelectron spectroscopy and quantum chemical calculations on the Au1,2-(Solv)n (Solv = C2H5OH, n-C3H7OH; n = 1-3 for Au-; n = 1 for Au2-). The microsolvation structures of these clusters and their corresponding neutrals are assigned by comparing calculations with experiments. In terms of overall regularity, the increasing solvation number (n) and carbon chain extension both can increase the stability of the anion. When n ≥ 2, these clusters have low-energy isomers, where conventional hydrogen bonds (HBs) compete with nonconventional HBs (NHBs). NHBs are dominant when n ≤ 2 and when n is increased, vice versa. Interestingly, a variety of theoretical calculations show that after the hydroxy H atom of the ethanol molecule forms a weak ionic HB with Au-, there are two lowest conformations of ethanol, trans and gauche, which could be coexisting in the molecular beams. Some theoretical methods also suggest that the gauche isomer is more stable than the trans one, which indicates that Au- may exist as a gold gauche effect similar to fluorine.

[Effect of traditional Chinese medicine for replenishing qi, nourishing yin and activating blood on renal Notch/Hes1 signaling in rats with diabetic nephropathy].

OBJECTIVE: To observe the effects of a traditional Chinese medicine (TCM) capsule for replenishing qi, nourishing yin and activating blood on Notch/Hes1 signaling pathway in the renal tissue and vascular endothelial CD34 and CD144 expressions in a rat model of diabetic nephropathy. METHODS: Rat models of early-stage diabetic nephropathy were established by left nephrectomy and high- fat and high- sugar feeding combined with intraperitoneal injection of STZ. The rats were randomized into model group, benazepril group, and high-, moderate-, and low-dose TCM capsule groups for corresponding treatments, with 6 normal rats as the control group. After 8 weeks of drug treatment, blood glucose and 24-h urinary albumin of the rats were measured, and the renal histopathology was observed with HE staining; Hes1 expression in the renal tissue was detected with immunohistochemical staining, and the renal expressions of CD34 and CD144 were detected using Western blotting. RESULTS: Compared with the normal control group, the rat models of diabetic nephropathy showed obvious abnormalities in 24- h urinary albumin and expressions of Hes1, CD34 and CD144d. The TCM capsule at both the high and moderate doses significantly reduced 24-h urinary albumin in the rats; the renal expressions of Hes1 and CD34 was significantly reduced in all the dose groups, and the expression of CD144 was significantly reduced in the high- dose group. Compared with benazepril group, the TCM capsule obviously reduced CD34 expression at all the 3 doses and lowered CD144 expression at the low dose. Histopathologically, the rats in the model group showed glomerular hypertrophy, increased mesenteric matrix, thickening and widening of the mesenteric membrane, and nodular hyperplasia. These pathologies were obviously alleviated by treatment with the TCM capsule at the high and moderate doses. CONCLUSIONS: The Traditional Chinese medicine (TCM) capsule for replenishing qi, nourishing yin and activating blood can reduce Hes1, CD34 and CD144 in kidney tissue of model rats, play a protective role on kidney function and delay the development of DN.

[Qibai Pingfei capsule alleviates inflammation and oxidative stress in a chronic obstructive pulmonary disease rat model with syndromes of Qi deficiency and phlegm and blood stasis by regulating the SIRT1/FoxO3a pathway].

Objective To explore the effect of Qibai Pingfei capsule (QPC) on the inflammation and oxidative stress in a chronic obstructive pulmonary disease (COPD) rat models with the syndromes of qi deficiency and phlegm and blood stasis by regulating the SIRT1/FoxO3a pathway. Methods A total of 80 male SD rats were randomly divided into 4 groups with 20 animals in each group: a non-diseased group, a non-treated diseased group, a diseased group treated with QPC, and a diseased group treated with placebo. The COPD rat models with the syndromes of qi deficiency and phlegm and blood stasis were then developed with established protocols. After the corresponding treatments, the serum levels of superoxide dismutase (SOD), malondialdehyde (MDA), interleukine 1ß (IL-1ß), and IL-2 were determined by ELISA; the protein levels of SIRT1 and FoxO3a were quantified by Western blot analysis; the mRNA levels of the SIRT1 and FoxO3a genes were also measured by real-time quantitative PCR. Results First of all, compared with the non-diseased group, the serum levels of MDA, IL-1ß, and IL-2 were elevated in the diseased group, while the level of SOD was reduced. Both mRNA and protein levels of SIRT1 decreased, while the levels of FoxO3a increased in the lung tissues of the diseased group. Compared with the diseased group treated with placebo, the diseased group treated with QPC had reduced serum levels of MDA, IL-1ß and IL-2, elevated SOD, increased mRNA and protein levels of SIRT1 and decreased levels of FoxO3a, thereby restoring their levels partially under the disease state. Conclusion QPC can alleviate inflammation and oxidative stress of COPD rats with syndrome of qi deficiency and phlegm and blood stasis effectively, potentially through regulating the expression level of the SIRT1/FoxO3a pathway.

The harpooning mechanism as evidenced in the oxidation reaction of the Al atom.

The harpooning mechanism has long been proposed for elementary reaction dynamics involving metals. It is characterized by an initial electron transfer (ET) process from the metal to the oxidant molecule. For the titled reaction Al + O2, the ET distance can be predicted to be 2.6 Å by simply calculating the energy difference between the ionization energy of the Al atom and the electron affinity of the O2 molecule. Hereby we experimentally derived the maximum impact parameter bmax of 2.5 ± 0.2 Å for the titled reaction, in consistency with the predicted ET distance. This derivation of bmax was achieved by using the crossed molecular beam experiment at a collision energy of 507 cm-1 (i.e. 1.45 kcal mol-1) with a high resolution time-sliced ion velocity imaging detection of the state-selective AlO products based on the (1 + 1) resonance-enhanced multiphoton ionization. The small rotational constant of the AlO(X2Σ+) radical (Be = 0.6413 cm-1) facilitated the formation of the AlO(v = 0) products in high rotational levels up to the energetically limited state, Nmax = 52, with an almost zero velocity mapping. Hence, in this extreme angular momentum disposal case, the collisional orbital angular momentum l was nearly completely channeled into the product rotational angular momentum as a consequence of the conservations of energy and angular momentum, offering a reaction system that breaks the restriction of kinematically favored mass combination in order to obtain information on the impact parameters. The present study yields the first direct derivation of bmax from the maximum rotational level of products under the experimental condition with the recoil energy E'T ≈ 0. This, in turn, provides solid evidence in supporting the harpooning mechanism.

Vibrationally mediated photodissociation of CH3I [v1 = 1] at 277.5 nm: the vibrationally adiabatic process.

From the photofragment translational spectra of C-H symmetric stretch excited CH3I [v1 = 1, v2 = 0] photodissociatioin at 277.5 nm, the vibrational distribution of photofragments CH3 (v1 = 0, v2 = 0), (0,1), (1,0), (1,1) in the I* channel are measured to be 0.02, 0.02, 0.47, 0.25, and those of CH3 (1,0), (1,1) in the I channel are 0.04, 0.05, respectively. It shows that most of the dissociated CH3I [1,0] retain the C-H symmetric stretch vibration v1 = 1 in the photofragments CH3, and the vibrational distribution in umbrella bending mode is not seriously affected by the original C-H symmetric stretch excitation. The photodissociation of CH3I [1,0] mainly follows the vibrationally adiabatic process. The original vibrational excitation [v1 = 1] of CH3I is quite like a spectator, and the intramolecular vibrational-energy redistribution (IVR) does not play obvious part during photodissociation.

Rotamers and isotopomers of 3-chloro-5-fluoroanisole studied by resonant two-photon ionization spectroscopy and theoretical calculations.

The ab initio and density functional theory (DFT) calculations reveal that two rotamers, denoted by cis and trans 3-chloro-5-fluoroanisole (3C5FA), are stable for each of the S(0), S(1), and D(0) states. In the one-color resonant two-photon ionization (R2PI) spectra, the band origins of the S(1)←S(0) electronic transition (0(0) bands) of cis(35)Cl-3C5FA and cis(37)Cl-3C5FA are both located at 36,468 ± 3 cm(-1), while the 0(0) bands of trans(35)Cl-3C5FA and trans(37)Cl-3C5FA are found to be 36,351 ± 3 and 36,354 ± 3 cm(-1). The two rotamers display very similar vibrational frequencies in the S(1) state, and the observed active modes mainly involve the in-plane ring deformation vibrations. By the two-color R2PI spectroscopy, the adiabatic ionization energies (IEs) of both isotopomers of 3C5FA are determined to be 69,720 ± 15 cm(-1) for the cis rotamer and 69,636 ± 15 cm(-1) for the trans rotamer. The substitution, conformation, and isotope effects on the properties of 3C5FA, including the molecular structures, vibrational frequencies, and electronic transition and ionization energies, were also discussed in detail.

Photofragment translational spectroscopy of CH3I at 225 nm--with the high excitation of the symmetric stretch vibration of CH3 fragment.

The photodissociation dynamics of CH(3)I at 225 nm is studied on our high resolution mini-TOF photofragment translational spectrometer. The photofragment translational spectra of the I* and the I channels via parallel (∥) and perpendicular (⊥) transitions, i.e., of the four pathways (3)Q(0), (3)Q(0) ← (1)Q(1), (1)Q(1), and (1)Q(1) ← (3)Q(0), are obtained with both the symmetric stretch (ν(1)) and the umbrella (ν(2)) vibrational modes of the CH(3) fragments partially resolved. The strong excitation of the symmetric stretch mode (ν(1)) is revealed in both the I and the I* channels. The branching fractions for the four pathways (0.09 for (3)Q(0), 0.03 for (3)Q(0) ← (1)Q(1), 0.34 for (1)Q(1), and 0.54 for (1)Q(1) ← (3)Q(0)) show that the parallel transition ((3)Q(0) ← X) is the major and the I channel is dominant in the photodissociation of CH(3)I at 225 nm. The curve-crossing probability is found to be 0.86 for (1)Q(1) ← (3)Q(0) but 0.08 for (3)Q(0) ← (1)Q(1).