Theory of nonradiative decay from the lowest singlet state of benzene: Excess energy dependence

1988 ◽  
Vol 53 (9) ◽  
pp. 1902-1909
Author(s):  
Makoto Takahashi ◽  
Tadaaki Ikoma ◽  
Yuichi Fujimura ◽  
Azumao Toyota ◽  
Takeshi Nakajima
Keyword(s):  
Energy Dependence ◽  
Internal Conversion ◽  
Excess Energy ◽  
Electronic Relaxation ◽  
Time Model ◽  
Model Calculations ◽  
Nonradiative Decay ◽  
Drastic Increase ◽  
Nonradiative Decay Rate ◽  
The Difference

A time-independent Green function formalism is developed to study the excess energy dependence on the nonradiative decay in the S1 state of benzene. Effects of purely electronic relaxation (internal conversion, IC) and intramolecular vibrational redistribution, IVR, are taken into account at the same time. Model calculations show that the drastic increase in the nonradiative decay rate at around 3 000 cm-1 excess energy is due to the same onset of both IC and IVR rates. Our theory can explain the difference in rate constant between IVR and IC observed by Moss and Parmenter.

Excess energy dependence of internal conversion in the S1 state of azulene

1988 ◽  
Vol 89 (7) ◽  
pp. 4441-4443 ◽  
Author(s):  
Sudhir K. Kulkarni ◽  
Jonathan E. Kenny
Keyword(s):  
Energy Dependence ◽  
Internal Conversion ◽  
Excess Energy

Isopotential points in square-wave voltammetry of reversible electrode reactions

2009 ◽  
Vol 74 (10) ◽  
pp. 1489-1501 ◽  
Author(s):  
Marina Zelić ◽  
Milivoj Lovrić
Keyword(s):  
Square Wave Voltammetry ◽  
Electrode Reaction ◽  
Time Model ◽  
Model Calculations ◽  
Square Wave ◽  
Electrode Reactions ◽  
Wave Voltammetry ◽  
Electron Transfer Processes ◽  
Diagnostic Criterion ◽  
First Time

Isopotential points in square-wave voltammetry are described for the first time. Model calculations and real measurements (performed with UO22+ and Eu3+ in perchlorate and bromide solutions, respectively) indicate that such an intersection could be observed when backward components of the net response, resulting from an increase in frequency or reactant concentration, are presented together. The electrode reaction should be fully reversible because quasireversible or slower electron transfer processes give the isopoints only at increasing reactant concentrations but not at increasing square-wave frequencies. The effect could be used as an additional diagnostic criterion for recognition of reversible electrode reactions where products remain dissolved in the electrolyte solution.

Abstract 14721: Impact of Covid-19 on Cardiology Consultation in Tertiary Care Hospital of a Developing Country

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
ghufran adnan ◽  
Osman Faheem ◽  
Maria Khan ◽  
Pirbhat Shams ◽  
Jamshed Ali
Keyword(s):  
Emergency Department ◽  
Tertiary Care ◽  
Reduction Rate ◽  
Care Hospital ◽  
Chi Square ◽  
Coronary Syndrome ◽  
Significant Difference ◽  
Drastic Increase ◽  
Chi Square Test ◽  
The Difference

Introduction: COVID-19 pandemic has overwhelmed the healthcare system of Pakistan. There has been observation regarding changes in pattern of patient presentation to emergency department (ED) for all diseases particularly cardiovascular. The aim of the study is to investigate these changes in cardiology consultations and compare pre-COVID-19 and COVID-19 era. Hypothesis: There is a significant difference in cardiology consultations during COVID era as compared to non-COVID era. Method: We collected data retrospectively of consecutive patients who visited emergency department (ED) during March-April 2019 (non-COVID era) and March-April 2020 (COVID era). Comparison has been made to quantify the differences in clinical characteristics, locality, admission, type, number, and reason of Cardiology consults generated. Results: We calculated the difference of 1351 patients between COVID and non-COVID era in terms of cardiology consults generated from Emergency department, using Chi-square test. Out of which 880 (59%) are male with mean age of 61(SD=15). Analysis shows pronounced augmentation in number of comorbidities [Hypertension(6%), Chronic kidney disease (6%), Diabetes (5%)] but there was 36% drop in total cardiology consultations and 43% reduction rate in patient’s ED visit from other cities during COVID era. There was 60% decrease in acute coronary syndrome presentation in COVID era, but fortuitously drastic increase (30%) in type II myocardial injury has been noted. Conclusion: There is a remarkable decline observed in patients presenting with cardiac manifestations during COVID era. Lack in timely care could have a pernicious impact on outcomes, global health care organizations should issue directions to adopt telemedicine services in underprivileged areas to provide timely care to cardiac patients.

scholarly journals The role of vibrationally excited oxygen and nitrogen in the ionosphere during the undisturbed and geomagnetic storm period of 6-12 April 1990

1998 ◽  
Vol 16 (5) ◽  
pp. 589-601 ◽  
Author(s):  
A. V. Pavlov
Keyword(s):  
Loss Rate ◽  
Boltzmann Distribution ◽  
Rate Coefficients ◽  
Ion Chemistry ◽  
Vibrationally Excited ◽  
Model Calculations ◽  
F Region ◽  
Neutral Temperature ◽  
The Difference ◽  
Excited Nitrogen

Abstract. We present a comparison of the observed behavior of the F-region ionosphere over Millstone Hill during the geomagnetically quiet and storm periods of 6–12 April 1990 with numerical model calculations from the IZMIRAN time-dependent mathematical model of the Earth's ionosphere and plasmasphere. The major enhancement to the IZMIRAN model developed in this study is the use of a new loss rate of O+(4S) ions as a result of new high-temperature flowing afterglow measurements of the rate coefficients K1 and K2 for the reactions of O+(4S) with N2 and O2. The deviations from the Boltzmann distribution for the first five vibrational levels of O2(v) were calculated, and the present study suggests that these deviations are not significant. It was found that the difference between the non-Boltzmann and Boltzmann distribution assumptions of O2(v) and the difference between ion and neutral temperature can lead to an increase of up to about 3 or a decrease of up to about 4 of the calculated NmF2 as a result of a respective increase or a decrease in K2. The IZMIRAN model reproduces major features of the data. We found that the inclusion of vibrationally excited N2(v > 0) and O2(v > 0) in the calculations improves the agreement between the calculated NmF2 and the data on 6, 9, and 10 April. However, both the daytime and nighttime densities are reproduced by the IZMIRAN model without the vibrationally excited nitrogen and oxygen on 8 and 11 April better than the IZMIRAN model with N2(v > 0) and O2(v > 0). This could be due to possible uncertainties in model neutral temperature and densities, EUV fluxes, rate coefficients, and the flow of ionization between the ionosphere and plasmasphere, and possible horizontal divergence of the flux of ionization above the station. Our calculations show that the increase in the O+ + N2 rate factor due to N2(v > 0) produces a 5-36 decrease in the calculated daytime peak density. The increase in the O++ O2 loss rate due to vibrational-ly excited O2 produces 8-46 reductions in NmF2. The effects of vibrationally excited O2 and N2 on Ne and Te are most pronounced during the daytime.Key words. Ion chemistry and composition · Ionosphere – atmosphere interactions · Ionospheric disturbances

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