The ultraviolet absorption spectrum of methyl diimide vapor

1977 ◽  
Vol 55 (8) ◽  
pp. 1396-1400 ◽  
Author(s):  
S.K. Vidyarthi ◽  
C. Willis ◽  
R.A. Back
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Vapor Phase ◽  
Vibrational Analysis ◽  
Deformation Mode ◽  
Vibrational Structure ◽  
Ultraviolet Absorption Spectrum ◽  
Valence Shell ◽  
Long Wavelength ◽  
Rydberg Transitions

The vapor phase absorption spectra of CH3N=NH and CH3N=ND have been measured from 160–450 nm. There are three prominent features centered at 360 nm (ε = 6 M−1 cm−1), 208 nm (ε = 710 M−1 cm−1), and 170 nm (s = 2080 M−1 cm−1). The weak near-uv band is assigned to the valence shell transition π* ← n+ while the two far-uv bands are attributed to the 3s ← n+ and 3p ← n+ Rydberg transitions. The band at 208 nm has resolved vibrational structure on the long wavelength tail and a vibrational analysis shows the main progression excited is the ν10′ CNN deformation mode.

Infrared and Electronic Absorption Spectra of Isoquinoline

1970 ◽  
Vol 24 (3) ◽  
pp. 344-347 ◽  
Author(s):  
R. Ammini Amma ◽  
S. N. Thakur ◽  
K. P. R. Nair
Keyword(s):  
Absorption Spectrum ◽  
Electronic Absorption Spectrum ◽  
Absorption Spectra ◽  
Vapor Phase ◽  
Electronic Absorption ◽  
Ir Spectrum ◽  
Electronic Absorption Spectra ◽  
Vibrational Analysis

The ir spectrum of isoquinoline has been investigated in the region 700–4000 cm−1. The observed frequencies have been correlated to the Raman frequencies and assigned to different modes of vibrations. The electronic absorption spectrum of the molecule has also been recorded in vapor phase in the region 2900–3200 Å. The system has been assigned to n–π* transition with the electronic origin at 31 984 cm−1. A vibrational analysis for the system is proposed.

The Near-ultraviolet Absorption Spectrum of Diimide in Liquid Ammonia and its Decomposition between −65 and −38 °C

1974 ◽  
Vol 52 (13) ◽  
pp. 2513-2515 ◽  
Author(s):  
R. A. Back ◽  
C. Willis
Keyword(s):  
Absorption Spectrum ◽  
Gas Phase ◽  
Room Temperature ◽  
Liquid Ammonia ◽  
Vibrational Structure ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum ◽  
First Order ◽  
Rapid Decomposition ◽  
Near Ultraviolet

The near-ultraviolet absorption spectrum of diimide in liquid ammonia at −50 °C is shifted about 500 Å to the red compared with the gas-phase spectrum, with λmax = 4000 Å. The spectrum is also broadened and the vibrational structure largely obscured. It is suggested that hydrogen bonding is responsible for these changes.Diimide is much more stable in liquid ammonia between −65 and −38 °C than in the gas phase at room temperature. A first-order decay is observed with Arrhenius parameters of A = 1.9 × 103 s−1 and E = 6.6 kcal/mol; this is always preceded by a more rapid, higher-order initial decay which may be related to the rapid decomposition observed during vaporization.

The A2Πi–X2Πi absorption spectrum of BrO

1981 ◽  
Vol 59 (12) ◽  
pp. 1908-1916 ◽  
Author(s):  
M. Barnett ◽  
E. A. Cohen ◽  
D. A. Ramsay
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Ground State ◽  
Flash Photolysis ◽  
Absorption Bands ◽  
Long Wavelength ◽  
Numbering Scheme ◽  
Ozonized Oxygen ◽  
Good Agreement

Absorption spectra of isotopically enriched 81Br16O and of normal BrO have been obtained by the flash photolysis of mixtures of bromine and ozonized oxygen. Rotational analyses are given for the 7–0, 12–0, 18–0, 19–0, 20–0, 21–0, 7–1, and 20–1 A2Π3/2–X2Π3/2 sub-bands of 81Br16O. The value for [Formula: see text] is found to be 722.1 ± 1.1 cm−1 in good agreement with the value calculated from microwave constants. Several additional bands have been found at the long wavelength end of the spectrum, necessitating a revision of the vibrational numbering scheme for both the emission and absorption bands. "Hot" bands up to ν″ = 6 have been observed in the absorption spectrum for the 2Π3/2 component of the ground state but no bands have yet been identified from the 2Π1/2 component.

Phenyl Substitution Effects on Triplet–Triplet Absorption Spectra: I. Study of 1,3,6,8-Tetraphenylpyrene

1975 ◽  
Vol 53 (21) ◽  
pp. 3269-3275 ◽  
Author(s):  
C. Rullière ◽  
E. C. Colson ◽  
P. C. Roberge
Keyword(s):  
Absorption Spectrum ◽  
Triplet State ◽  
Absorption Spectra ◽  
Rate Constant ◽  
Theoretical Calculations ◽  
Vibrational Structure ◽  
Substitution Effects ◽  
Quenching Rate ◽  
Diffusion Controlled ◽  
Quenching Rate Constant

The triplet–triplet (T–T) absorption spectrum of 1,3,6,8-tetraphenylpyrene (TPP) was measured from 400 to 620 nm. The data obtained are compared with theoretical calculations using the Ruedenberg–Scherr FEMO model. A planar triplet state is evidenced by fine vibrational structure. The T–T quenching rate constant measured (1.3 ± 0.1 × 109 M−1 s−1) is 20% of the expected diffusion-controlled value.

Assignment and vibrational analysis of the 600 nm absorption band in the phenoxyl radical and some of its derivatives

1993 ◽  
Vol 71 (10) ◽  
pp. 1655-1662 ◽  
Author(s):  
Linda J. Johnston ◽  
N. Mathivanan ◽  
Fabrizia Negri ◽  
Willem Siebrand ◽  
Francesco Zerbetto
Keyword(s):  
Ab Initio ◽  
Vibrational Analysis ◽  
Deformation Mode ◽  
Phenoxyl Radical ◽  
Dominant Mode ◽  
Vibrational Structure ◽  
Large Intensity ◽  
Phenyl Rings ◽  
Semi Empirical ◽  
Rigid Matrix

An experimental and theoretical study is reported of the 600 nm band system of phenoxyl and several methoxy substituted phenoxyls. These radicals, generated in freon, show a diffuse band in this region with a vibrational structure that is incompletely resolved but consistent with the 500 cm−1 "progression" observed earlier for phenoxyl in the vapour and in a rigid matrix. The low intensity of this band is considerably enhanced by ortho-methoxy substitution. To establish its assignment and analyze its structure, semi-empirical and ab initio quantum chemical calculations have been performed. It is found that, on the basis of the ordering of the states and the magnitude of their transition moments, all calculations favour a ππ* (2B2 → 2A2) rather than the earlier proposed nπ* assignment for this band. Of the methods used, only the (ab initio) CASSCF method is found to be able to simulate the observed vibrational structure adequately. This simulation is based on optimized structures and vibrational force fields calculated for the 1B2 and 1A2 states of phenoxyl. It identifies the dominant mode of about 500 cm−1 as ν6a the characteristic deformation mode of phenyl rings, but shows that higher members of the "progression" receive large intensity contributions from higher frequency modes. The chosen assignment and the assignments of higher-energy transitions reported in the literature are compared with those for the better known benzyl radical. It is shown that some of the phenoxyl assignments reported in the literature contain errors.

Near-Ultraviolet Absorption Spectrum of m-Chlorobenzonitrile in Vapor Phase

1967 ◽  
Vol 21 (6) ◽  
pp. 423-423 ◽  
Author(s):  
D. Sharma ◽  
A. N. Pathak
Keyword(s):  
Absorption Spectrum ◽  
Vapor Phase ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum ◽  
Near Ultraviolet

Rotational and Vibrational Analysis of the First Singlet Transition (1B2 ← 1A1) of Isobenzofuran

1975 ◽  
Vol 53 (19) ◽  
pp. 1814-1824 ◽  
Author(s):  
M. J. Robey ◽  
I. G. Ross
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Vibrational Analysis ◽  
Vibrational Structure ◽  
Rotational Structure ◽  
Type B ◽  
State Structure ◽  
Detailed Structure ◽  
Rotational Constants ◽  
Singlet Transition

The absorption spectrum of isobenzofuran vapor has been photographed at resolving powers in excess of 300 000. The vibrational structure is straightforward, involving totally symmetric vibrations only. The rotational structure of a band at 0 + 858 cm−1 has been analyzed as a type B band, leading to the assignment of the transition as 1B2 ← 1A1. The detailed structure of the band is described. The changes in the rotational constants are ΔA + 0.000124, ΔB −0.000122, and ΔC −0.00052 cm−1. A calculated excited state structure compatible with these results is proposed.

The vapor-phase ultraviolet absorption spectrum of phenylsilane and phenylsilane-αd3

1987 ◽  
Vol 126 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Walter J Balfour ◽  
K.S Chandrasekhar ◽  
Anne E Morrison
Keyword(s):  
Absorption Spectrum ◽  
Vapor Phase ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum

scholarly journals The Near-ultraviolet Absorption Spectrum of Diimide Vapor

1974 ◽  
Vol 52 (6) ◽  
pp. 1006-1012 ◽  
Author(s):  
R. A. Back ◽  
C. Willis ◽  
D. A. Ramsay
Keyword(s):  
Absorption Spectrum ◽  
Bond Length ◽  
Gas Phase ◽  
Absorption Spectra ◽  
Ground State ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum ◽  
Near Ultraviolet ◽  
Bending Mode ◽  
Franck Condon

Absorption spectra of N2H2 and N2D2 in the gas phase have been obtained in the region 3000–4300 Å, consisting of about 30 diffuse bands for each compound. Long progressions in the spectra are attributed to excitation of the H—N=N bending mode, v2′, in the upper state, with much shorter progressions arising from the N=N stretching mode, v3′; values of v2′ = 1215 and 910 cm−1 and v3′ = 1550 and 1440 cm−1 were estimated for N2H2 and N2D2 respectively.The spectra are attributed to the 1Bg ← 1Ag(π* ← n+) transition of trans diimide, probably made allowed by vibronic interaction. From Franck–Condon calculations the H—N=N angle in the upper state was estimated to be 132 ± 2°, an increase of 25° from the ground-state value; the increase in the N=N bond length was estimated to be about 0.05 Å.

The absorption spectrum of trans-diimide (N2H2) in the vacuum ultraviolet region

1981 ◽  
Vol 59 (3) ◽  
pp. 506-517 ◽  
Author(s):  
P. S. Neudorfl ◽  
R. A. Back ◽  
A. E. Douglas
Keyword(s):  
Absorption Spectrum ◽  
Gas Phase ◽  
Vacuum Ultraviolet ◽  
Singlet State ◽  
Ultraviolet Region ◽  
Ultraviolet Absorption Spectrum ◽  
Rotational Analysis ◽  
Trans Conformation ◽  
Vacuum Ultraviolet Region ◽  
Rydberg Transitions

The vacuum ultraviolet absorption spectrum of trans-diimide (N2H2) in the gas phase has been re-examined between 1800 and 1300 Å, using diimide prepared by the thermal decomposition of sodium tosylhydrazide. Two band systems were observed, designated [Formula: see text] and [Formula: see text], with origins at 1727 and 1473 Å, which have been assigned to the Rydberg transitions 3pπ(bu) ← n+ and 4pπ(bu) ← n+ respectively. Both systems show long progressions in v2′, the N—N—H symmetric bending frequency, and short progressions in v3′, the symmetric N—N stretching frequency.The [Formula: see text] system has well-resolved rotational J type structure in some bands, and the rotational analysis showed that the ground state is a totally symmetric singlet state of C2h symmetry (planar trans-N2H2 isomer), and that the system arises from a 1Bu ← 1Ag transition. Rotational constants obtained for the 0–0 band of the [Formula: see text]-state were A = 15.63, B = 1.32, and C = 1.22 cm−1, and the values of rH−N = 1.028 Å, rH−N = 1.167 Å, and [Formula: see text] were estimated from them assuming a planar trans conformation.

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