Resonance fluorescence intensities and vibrational assignments in the A2B2 state of NO2

1982 ◽  
Vol 60 (8) ◽  
pp. 1081-1087 ◽  
Author(s):  
J. C. D. Brand ◽  
K. J. Cross ◽  
A. R. Hoy
Keyword(s):  
Radiative Lifetime ◽  
Rotational Constant ◽  
Resonance Fluorescence ◽  
Final State ◽  
Vibrational Assignments ◽  
Quantum Numbers ◽  
A Value ◽  
Franck Condon

The intensity of NO2 resonance fluorescence excited at several wavelengths in the range 5930–6480 Å has been measured as a function of final state vibrational quantum numbers. Calculations based on these Franck–Condon profiles establish the relative vibrational assignments of five bands in the [Formula: see text] system. In one case, the similarities between a Ka = 1 and a Ka = 6 profile lead to a value of the à 2B2A rotational constant of ~3.0 cm−1. The influence of Franck–Condon profiles on the radiative lifetime of pure à 2B2 states is investigated.

scholarly journals Dynamics of the B 3Π(0u+) and A 3Π(1u) States of Chlorine by Laser Induced Fluorescence

1992 ◽  
Vol 12 (1-2) ◽  
pp. 75-84 ◽  
Author(s):  
E. Martínez ◽  
F. J. Basterrechea ◽  
B. Cabañas ◽  
P. Puyuelo ◽  
M. R. López
Keyword(s):  
Radiative Lifetime ◽  
Laser Induced Fluorescence ◽  
Trial And Error ◽  
Interference Effects ◽  
A Value ◽  
Vibrational Levels ◽  
Franck Condon

Chlorine B 3Π(0u+) state lifetimes have been measured by laser-induced fluorescence in several predissociated (υ′ = 14–19,21) and non-predissociated (υ′ = 5–12) levels. Trial and error Franck-Condon calculations have been performed to check the nature and position of the predissociating state. The results have been used to give a value of Re for the A 3Π(1u) state responsible for predissociation, Re = 2.48 ± 0.01 Å. The obtained data show that interference effects due to crossing between B and A states modify the lifetimes of the B state appreciably. The inadequacy of the low-lying vibrational levels region, i.e. υ′ < 8, to measure the radiative lifetime of the B state (τR(B)) is shown. Previous values for τR(B) can therefore be affected by considerable errors.

Vibration-rotation bands and rotational constants of dideuteroacetylene

1955 ◽  
Vol 232 (1190) ◽  
pp. 291-309 ◽  
Keyword(s):  
Resolving Power ◽  
Vibrational States ◽  
Absorption Bands ◽  
Rotational Constants ◽  
Vibrational Assignments ◽  
Vibrational Anharmonicity ◽  
A Value ◽  
Vibrational Levels ◽  
Vibration Rotation ◽  
Very High

Nine vibrational absorption bands of dideutero-acetylene have been examined with very high resolving power. The rotational constants have been determined for the vibrational levels concerned, and the coefficients α i have been determined with more convincing accuracy than previously. In some of the bands the Q branches have been resolved, so that the l -doubling coefficients q i could be derived, and details could be established about the doublet components in some II levels. The results emphasize the need of high resolution if the vibrational assignments are to be unambiguous, and if reliable values of the rotational constants are to be derived. A value of B e has been obtained, and the vibrational anharmonicity coefficients have been considered briefly. Estimates of the centrifugal stretching constants D i in different vibrational states have been made, and one anomalous case has been found.

Thioamide spectroscopy: long path length absorption and quantum chemical studies of thioformamide vapour, CHSNH2/CHSND2

1987 ◽  
Vol 65 (9) ◽  
pp. 2100-2105 ◽  
Author(s):  
R. H. Judge ◽  
D. C. Moule ◽  
J. D. Goddard
Keyword(s):  
Path Length ◽  
Lower State ◽  
Amino Groups ◽  
Vibrational Assignments ◽  
Transition Formula ◽  
Out Of Plane ◽  
Chemical Studies ◽  
Moderate Resolution ◽  
Quantum Chemical Studies ◽  
Franck Condon

The 270 nm absorption spectra of thioformamide, CHSNH2 and CHSND2, have been photographically recorded under conditions of long path length (88 m) and moderate resolution (7.5 Å/mm). The absorption was assigned to the electron promotion, nS → π* (CS), and to the electronic transition, [Formula: see text]. The spectra proved to be complex, highly congested and somewhat diffuse which limited the extent of the vibrational assignments. Progressions in five members were observed in both CHSNH2/CHSND2 in intervals of 516/496 cm−1 which were assigned to ν10, the out-of-plane aldehyde wagging mode. It was concluded on Franck–Condon grounds that the [Formula: see text] molecule was non-planar at the aldehyde center. Structures and vibrational frequencies were calculated for the [Formula: see text] and the[Formula: see text] electronic states at the 3-21G* SCF level. The calculations confirmed that the lower state was strictly planar and predicted that both the aldehyde and amino groups were pyramidal in the upper electronic state.

scholarly journals The chemical constant of hydrogen vapour and the entropy of crystalline hydrogen

1931 ◽  
Vol 130 (813) ◽  
pp. 367-379 ◽  
Keyword(s):  
Vapour Pressure ◽  
Low Temperatures ◽  
Hydrogen Gas ◽  
Para Hydrogen ◽  
Bose Statistics ◽  
Hydrogen Molecules ◽  
Quantum Numbers ◽  
A Value ◽  
Classical Statistics ◽  
Chemical Constant

In a paper called "The Chemical constant of Hydrogen Vapour and the failure of Nernst's Heat Theorem," R. H. Fowler has investigated the vapour pressure of hydrogen crystals at low temperature; taking account of the existence of two sorts of hydrogen molecules, namely, ortho-hydrogen with even rotational quantum numbers and para-hydrogen with odd rotational quantum numbers, which retain their individuality over long periods at very low temperatures. By the use of the classical statistics, he was able to show that at very low temperatures hydrogen, as obtained by cooling hydrogen gas from ordinary temperatures, ought to have very nearly the experimentally observed chemical constant. Since the theory of the specific heat of hydrogen yielded correct values at low temperatures, it followed that at ordinary temperatures also his theory would yield a correct value for the chemical constant. Finally from the form of the partition function for hydrogen gas, Fowler attempted to obtain inferences concerning the validity of Nernst's heat theorem. By the use of the classical statistics fairly accurate results were obtained. But we shall find that when we make use of the Einstein-Bose statistics-the correct statistics for an assembly of hydrogen moleclues-a result will be obtained for the vapour pressure of hydrogen crystals at low temperatures which will furnish a value for the chemical constant of hydrogen in even closer agreement with experiment than Fowler's result.

The ν3 vibration–rotation band of DCP and the equilibrium structure of methinophosphide

1982 ◽  
Vol 60 (3) ◽  
pp. 304-306 ◽  
Author(s):  
Jacques Lavigne ◽  
Aldée Cabana
Keyword(s):  
Force Constant ◽  
Rotational Constant ◽  
Equilibrium Structure ◽  
Moment Of Inertia ◽  
Rotation Band ◽  
A Value ◽  
Internuclear Distances ◽  
Vibration Rotation

The ν3 band of D12CP(C—P stretching) has been recorded at a resolution of about 0.03 cm−1. The band centre, ν0, is found to be at 1231.4025(6) cm−1, whereas a force constant calculation had previously given a value of 1216 cm−1. The rotational constant B3 is determined and this allows the calculation of Be since the constants B1 and B2 are already known. Finally, the equilibrium moment of inertia, Ie, of the D12CP molecule is calculated. Since Ie for the H12CP molecule is also known, the equilibrium internuclear distances of methinophosphide may be calculated. One obtains: re (C—H) 1.0666(2) Å, and re(C≡P) 1.54020(3) Å.

ON THE CLUSTER-MODEL DESCRIPTION OF COLLISIONS

2011 ◽  
Vol 20 (04) ◽  
pp. 769-774
Author(s):  
DANIEL BAYE
Keyword(s):  
Cluster Model ◽  
Radiative Capture ◽  
Nuclear Astrophysics ◽  
Model Description ◽  
Group Method ◽  
Final State ◽  
Full Account ◽  
Scattering States ◽  
Quantum Numbers ◽  
Three Body

With simple cluster wave functions describing the colliding nuclei, the resonating-group method allows treating collisions realistically with full account of antisymmetrization and of good quantum numbers. The introduction of generator coordinates leads to a striking simplification by allowing the systematic use of Slater determinants. Reactions involving bound and scattering states simultaneously, such as radiative-capture reactions in nuclear astrophysics, are a particularly rich field of applications. In recent years, the microscopic cluster model has evolved to the study of three-body scattering which appears as a final state in a number of processes. The challenge is now to extend microscopic descriptions of collisions to ab initio calculations with realistic forces.

Die Bestimmung von Molekülkonstanten aus nicht aufgelösten Bandenspektren am Beispiel des PO-β-Systems

1966 ◽  
Vol 21 (11) ◽  
pp. 1878-1883
Author(s):  
H. Meinel ◽  
L. Krauss
Keyword(s):  
Correction Term ◽  
Rotational Constant ◽  
Nuclear Motion ◽  
Cubic Equation ◽  
System A ◽  
Quantum Numbers ◽  
Vibrational Levels ◽  
Doublet Splitting ◽  
Potential Curves

For 2∑-2Πa transitions (e. g. PO β-system), a method is described for calculation of rotational constants B (ν) from the doublet splitting of the bandheads. In that way the classification of both the violet and the red shaded PO β-bands (some 30 bands are new analysed) into one system can be shown, which seemed to be doubtful recently. From the discrepancies between the observed and the calculated additional heads in some subbands the rotational constant D has been evaluated, which plays an important part particularly for higher values of J as correction term in our calculation. Small systematic deviations in the graph of the rotational constant B (ν) for some sequences Δν=ν′-ν″ are interpreted as an indication for the interaction between electronic and nuclear motion; the effect corresponds to a deformation in the flanks of the potential curve in the order of 0.001 Å for higher vibrational quantum numbers (ν>5). The potential curves for the PO β- and γ-system have been computed, and from their relative position the observed perturbation of the level ν′=10 (β-system) and the range of perturbation starting at ν′=0 (γ-system) is explained. By calculation of the band origins a cubic equation for the vibrational levels of the B2∑-state is deduced. The extrapolation of the differences between two successive vibrational levels yields a new value of dissociation energy D00 (PO) =5.15 eV.

Electric birefringence in molecular hydrogen

1968 ◽  
Vol 305 (1481) ◽  
pp. 259-269 ◽  
Keyword(s):  
Kerr Effect ◽  
Molecular Hydrogen ◽  
Rotational Constant ◽  
Kerr Constant ◽  
Theory Analysis ◽  
Electric Birefringence ◽  
Dilute Gas ◽  
A Value ◽  
Phase Sensitive ◽  
Phase Sensitive Detector

The theory of the Kerr effect (electric birefringence) of a dilute gas of diatomic molecules is developed, account being taken of the quantization of rotational energy. The theory leads to corrections to the classical formula for the molar Kerr constant which involve the ratio of the rotational constant hcB 0 to the thermal energy kT . These corrections are appreciable at normal temperatures for only a few hydrides; they are particularly important for molecular hydrogen. The Kerr effect has been observed in gaseous H 2 from -30 to +60°C and from 25 to 85 atm, a 6328 Å laser light source and phase-sensitive detector being used. The temperature dependence of the Kerr constant is in good agreement with the quantum theory. Analysis of the results yields a value for the hyperpolarizability γ of H 2 of (0∙28 ± 0∙03) x 10 -36 e. s. u. The Kerr constant of D 2 is also reported. The observed pressure dependence of the molar Kerr constant of H 2 is compared with theoretical results based on a calculation of the polarizability anisotropy of a pair of molecules.

scholarly journals Weak decays of heavy hadrons into dynamically generated resonances

2016 ◽  
Vol 25 (01) ◽  
pp. 1630001 ◽  
Author(s):  
Eulogio Oset ◽  
Wei-Hong Liang ◽  
Melahat Bayar ◽  
Ju-Jun Xie ◽  
Lian Rong Dai ◽  
...  
Keyword(s):  
Weak Interaction ◽  
Weak Decay ◽  
Final State ◽  
Hadron Interaction ◽  
Heavy Mesons ◽  
Weak Decays ◽  
Quantum Numbers ◽  
Unitary Approach ◽  
Chiral Unitary Approach ◽  
Interpretation Of Results

In this paper, we present a review of recent works on weak decay of heavy mesons and baryons with two mesons, or a meson and a baryon, interacting strongly in the final state. The aim is to learn about the interaction of hadrons and how some particular resonances are produced in the reactions. It is shown that these reactions have peculiar features and act as filters for some quantum numbers which allow to identify easily some resonances and learn about their nature. The combination of basic elements of the weak interaction with the framework of the chiral unitary approach allow for an interpretation of results of many reactions and add a novel information to different aspects of the hadron interaction and the properties of dynamically generated resonances.

Sign in / Sign up

Export Citation Format

Share Document