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 ABSORPTION SPECTRUM OF CF2

1967 ◽  
Vol 45 (7) ◽  
pp. 2355-2374 ◽  
Author(s):  
C. Weldon Mathews
Keyword(s):  
Absorption Spectrum ◽  
Electronic State ◽  
Ground State ◽  
Band System ◽  
Electronic States ◽  
Vibrational Structure ◽  
Rotational Structure ◽  
Transition Moment ◽  
High Dispersion ◽  
Parallel Type

The absorption spectrum of CF2 in the 2 500 Å region has been photographed at high dispersion, and the rotational structure of a number of bands has been analyzed. The analysis of the well-resolved subbands establishes that these are perpendicular- rather than parallel-type bands, as previously assigned. Further analysis shows that the upper and lower electronic states are of 1B1 and 1A1symmetries respectively, corresponding to a transition moment that is perpendicular to the plane of the molecule. In the upper electronic state, r0(CF) = 1.32 Å and [Formula: see text], while in the ground state, r0(CF) = 1.300 Å and [Formula: see text]. An investigation of the vibrational structure of the band system has shown that the vibrational numbering in ν2′ must be increased by one unit from earlier assignments, thus placing the 000–000 band near 2 687 Å (37 220 cm−1). A search between 1 300 and 8 500 Å showed two new band systems near 1 350 and 1 500 Å which have been assigned tentatively to the CF2 molecule.

Vibrational Analysis of the 2800 Å Band System of para-Dibromobenzene

1972 ◽  
Vol 50 (12) ◽  
pp. 1402-1408 ◽  
Author(s):  
S. M. Japar
Keyword(s):  
Excited State ◽  
High Resolution ◽  
Ground State ◽  
Band System ◽  
Vibrational Analysis ◽  
Type A ◽  
Strong Type ◽  
Type B ◽  
Sequence Structure ◽  
Extensive Sequence

The 2800 Å band system of p-dibromobenzene has been photographed under high resolution and an extended vibrational analysis has been carried out. The analysis is not inconsistent with the assignment of the system to a 1B2u ← 1Ag transition, by analogy with other p-dihalogenated benzenes. The observed spectrum can be explained in terms of a number of strong type-B vibronic bands and a considerably smaller number of type-A vibronic bands. The extensive sequence structure is adequately accounted for, and can be related to observations on other halogenated benzene molecules. Thirteen ground state and nine excited state fundamental vibrational frequencies have been assigned.

The electronic absorption spectrum of NHD

1979 ◽  
Vol 57 (5) ◽  
pp. 761-766 ◽  
Author(s):  
D. A. Ramsay ◽  
F.D. Wayne
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Electronic Absorption Spectrum ◽  
Electronic Absorption ◽  
Rotational Constants ◽  
Axis Switching

Rotational assignments are given for about 350 lines in the (0,9,0)–(0,0,0), (0,10,0)–(0,0,0), and (0,11,0)–(0,0,0) bands in the electronic absorption spectrum of NHD. The Σ and Δ sub-bands have been identified for the bands with ν2′ odd and the Π sub-band for the band with ν2′ even.Ground state rotational and spin–rotational constants have been determined. The principal constants in reciprocal centimetres are: A = 20.1162(32), B = 8.1114(16), C = 5.6681(16), εaa = −0.2324(51),εbb = −0.0373ε, εcc = −0.0019ε, where the error limits are 1σ. Term values are tabulated for both the ground and excited state levels.Several 'axis-switching' branches have been identified in agreement with the predictions of Hougen and Watson.

Spectrum of azulene. IV. Rotational analysis of the 0-0 band of the 3500 Ǻ transition

1968 ◽  
Vol 21 (12) ◽  
pp. 2835 ◽  
Author(s):  
AJ McHugh ◽  
DA Ramsay ◽  
IG Ross
Keyword(s):  
Fine Structure ◽  
Excited State ◽  
Type A ◽  
Resolving Power ◽  
Rotational Analysis ◽  
Type B ◽  
Rotational Constants ◽  
Multiple Line ◽  
Asymmetric Top ◽  
Low K

The bands of the 3500 Ǻ transition of azulene-do and azulene-ds show two unequal peaks 2.3 cm-l apart, followed by closely spaced fine structure. These bands have been analysed as type A bands of a planar, prolate asymmetric top. Rotational constants for both molecules in the excited state have been determined. The fine structure is due to multiple line coincidences in the high-J, low-K region of the qP branch. To each multiple line can be attributed a running number n = J+m, where m = J-K-1. Given sufficient resolving power, such "lines" should be rather commonly observed in type A and type B bands of large, planar, prolate molecules.

Rotational Structure in the (2,0) Band of the C2 Δ3/2–X2 Π1/2 Subsystem of SbO

1974 ◽  
Vol 52 (7) ◽  
pp. 592-598 ◽  
Author(s):  
S. B. Rai ◽  
B. Rai ◽  
D. K. Rai
Keyword(s):  
Excited State ◽  
Ground State ◽  
Rotational Structure ◽  
Third Order ◽  
Rotational Constants ◽  
The Third ◽  
Concave Grating ◽  
Combining States

The rotational structure in (2,0) band of C2Δ3/2–X2Π1/2 subsystem of SbO molecule has been photographed in the third order of a 35 ft concave grating spectrograph, and the rotational constants of the two combining states have been determined. It is found that the new rotational constants for the ground state are in agreement with those reported by Rai et al., but the constants for the excited state differ appreciably from those reported earlier by Rao and Rao. A small λ-type doubling (≈4.0 × 10−6 cm−1) is observed in the excited state. The isotopic lines due to 123SbO have also been observed.

Investigation of the Structure of the ν1 Band of Monochloroacetylene

1968 ◽  
Vol 23 (12) ◽  
pp. 2098-2099 ◽  
Author(s):  
Rauno Anttila ◽  
Mikko Huhanantti
Keyword(s):  
Excited State ◽  
Rotational Structure ◽  
Rotational Constants ◽  
A Value ◽  
Type Band

The ν1 band of monochloroacetylene was investigated. The rotational structure of this Σ-Σ type band was resolved and lines of both HCCCl35 and HCCCl37 were assigned. The rotational constants of these molecules were obtained both in the ground and the excited state. For the D constant of HCCCl35 a value of (4.8 ±1) × 10-8 cm-1 was obtained from the band. The constant was also computed theoretically and the result was 4.6 × 10-8 cm-1.

Conformational changes accompanying electronic excitation of trifluoronitrosomethane

1976 ◽  
Vol 54 (16) ◽  
pp. 2658-2668 ◽  
Author(s):  
R. D. Gordon ◽  
S. C. Dass ◽  
J. R. Robins ◽  
H. F. Shurvell ◽  
R. F. Whitlock
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Gas Phase ◽  
Conformational Changes ◽  
Ground State ◽  
Electronic Excitation ◽  
Excited Electronic State ◽  
Vibrational Structure ◽  
The Other ◽  
Transition Analysis

The 690 nm absorption spectrum of CF3NO has been studied in the gas phase at various temperatures and in the condensed phase at 77 K, and assigned to an (nπ*) transition. Analysis of the vibrational structure shows that, while only the eclipsed conformer is stable in the ground state, there are two stable isomers of comparable energy in the excited electronic state. One has an eclipsed conformation, but with the CF3 group tilted away from the oxygen atom. The other has a staggered conformation. In both of the excited state isomers the barrier to internal rotation is higher than in the ground state.

High-resolution study of the υ9 fundamental band of trans-glyoxal

2001 ◽  
Vol 79 (2-3) ◽  
pp. 479-482 ◽  
Author(s):  
D B Braund ◽  
A RH Cole
Keyword(s):  
Excited State ◽  
High Resolution ◽  
Ground State ◽  
Type B ◽  
Rotational Constants ◽  
Fundamental Band ◽  
Stretching Vibration ◽  
Resolution Study

The spectrum of trans-glyoxal has been recorded at a resolution of about 0.004 cm–1 in the region from 2770 to 2900 cm–1. 1549 lines have been assigned to the type B band due to the υ9 (bu) fundamental (antisymmetric C–H stretching vibration). The ground-state rotational constants confirm earlier values and new constants are determined for the excited state of υ9. PACS No.: 33.20E

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.

Rotational band contours in the 3280 Å electronic system of 2, 1, 3-benzothiadiazole

1969 ◽  
Vol 308 (1495) ◽  
pp. 537-545 ◽  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Vibrational Analysis ◽  
Electronic System ◽  
Type I ◽  
Rotational Analysis ◽  
Rotational Constants ◽  
Symmetry Species ◽  
Asymmetric Top ◽  
Band Type

Rotational analysis of band contours of the 0-0 band at 3280 Å and a 1-0 band at 3230 Å of the asymmetric top 2, 1, 3-benzothiadiazole have been carried out. The method used is that of computer simulation of the observed contour with the band type, i. e. rotational selection rules, and excited state rotational constants A ´, B ´, and C ´ as input data. It is shown that the 0-0 band is type B and therefore that the electronic assignment is 1 B 2 - 1 A 1 . The 1-0 band at 3230 Å is shown to be a type A band from which it follows that the vibration active in this band must be of symmetry species b 2 . The excited state rotational constants for the 1 B 2 electronic state are: A ´ = 0·1309±0·0003 cm -1 , B ´ = 0·0405±0·0001 cm -1 , C ´ = 0·0309±0·0001 cm -1 . The quoted uncertainties are those of the changes of the rotational constants and do not include those of the ground state. The excited state was assumed to be planar and the results support this assumption. One feature of the rotational constants is a slight decrease of I A . This, together with information from a vibrational analysis of the system, is consistent with an increase of the C 5 C 4 C 9 angle in the excited state. The origin of the 0-0 band is at 30410·5±0·2 cm -1 .

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