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Hot band

About: Hot band is a research topic. Over the lifetime, 2762 publications have been published within this topic receiving 60734 citations.


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Journal ArticleDOI
TL;DR: In this paper, the vibronic energy levels of a symmetrical nonlinear molecule in a spatially doubly degenerate electronic state which is split in first order by a doubly-degenerate vibrational mode are examined.
Abstract: This paper examines the vibronic energy levels of a symmetrical non-linear molecule in a spatially doubly degenerate electronic state which is split in first order by a doubly degenerate vibrational mode. The vibronic levels are classified by a quantum number, which in certain cases is formally related to the combined angular momentum of electronic and vibrational motion, and numerical values are obtained for the energies of these levels as functions of this quantum number and a dimensionless parameter measuring the magnitude of the electronic-vibrational coupling. It is shown that the selection rules for transitions from these vibronic levels to those of a non-degenerate electronic state allow changes in vibrational energy of any integral number of quanta, as though the Jahn-Teller effect were equivalent to a distortion which makes allowed vibrational transitions which would otherwise be forbidden. Numerical values are given for the oscillator strengths of vibronic absorption or emission bands involving transitions between a Jahn-Teller distorted state and an electronically non-degenerate state. It is found that in transitions from the latter to the former the vibrational structure of the electronic band exhibits two intensity maxima if the distortion is large.

747 citations

Journal ArticleDOI
TL;DR: In this paper, the infrared spectra of fully extended n-paraffin molecules from C 3 H 8 through n-C 19 H 40 were reported together with complete vibrational assignments based on frequency-phase curves and normal co-ordinate calculations.

681 citations

Journal ArticleDOI
TL;DR: In this article, normal coordinate calculations are carried out for all the inplane modes of octaethylporphyrinato-Ni (II) and its meso-deuterated and 15N substituted derivatives.
Abstract: Normal coordinate calculations are carried out for all the in‐plane modes of octaethylporphyrinato‐Ni (II) and its meso‐deuterated and 15N substituted derivatives. With 37 constants of a modified Urey–Bradley force field and a structural model with D4h symmetry, 59 resonance Raman lines (A1g+B1g +A2g+B2g) and 38 infrared bands (Eu) of these three molecules are assigned. The vibrational modes of the Raman active species are represented in terms of the Cartesian atomic displacement vectors. Based on the present results, some important resonance Raman lines of hemoproteins are interpreted. The so‐called ’’oxidation state maker’’ (Band IV) is due to an in‐phase breathing‐like mode of four pyrrole rings although being somewhat deformed by the large contribution of the Cα–N symmetric stretching term. The spin state sensitive Raman lines, namely, Band I and III, are associated mainly with methine bridge (Cα–Cm) stretching modes. Two prominent anomalously‐polarized Raman lines of hemoproteins around 1580 and 1300...

517 citations

Journal ArticleDOI
TL;DR: In this paper, a procedure that automatically identifies internal rotation modes and rotating groups during the normal mode vibrational analysis is outlined, and an improved approximation to the corrections for the thermodynamic functions is proposed.
Abstract: A procedure that automatically identifies internal rotation modes and rotating groups during the normal mode vibrational analysis is outlined, and an improved approximation to the corrections for the thermodynamic functions is proposed. The identification and the characterization of the internal rotation modes require no user intervention and make extensive use of the information imbedded in the redundant internal coordinates. Rigid-rotor internal rotation modes are obtained by fixing stretching, bending, and out-of-plane bending motions and solving the vibrational problem for the constrained system. Normal vibrational modes corresponding to internal rotations are identified by comparing them with the constrained modes. The atomic composition of the rotating groups is determined automatically and the kinetic energy matrix for internal rotation is given by either the constrained Wilson-G matrix or the Kilpatrick and Pitzer protocol. The potential periodicity, the rotating tops’ symmetry numbers, and the well-multiplicity are obtained using simple rules. These parameters can be altered by user input. An improved analytical approximation to the partition function for a one-dimensional hindered internal rotation has been developed that reproduces the accurate values tabulated by Pitzer and Gwinn to ±0.4% with a maximum error of 2.1%. This approximation is shown to behave better than previously available approximations over a wider range of regimes. The one-dimensional rotor treatment is generalized to give useful approximations to the multidimensional rotor thermodynamic functions that can be a good start for more thorough studies.

418 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20238
202214
202114
202019
20199
20189