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 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 .

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.

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.

Vibration-rotation bands of nitrous oxide

1951 ◽  
Vol 208 (1094) ◽  
pp. 326-331 ◽  
Keyword(s):  
Nitrous Oxide ◽  
Fine Structure ◽  
Ground State ◽  
Wave Length ◽  
The Other ◽  
Resolving Power ◽  
Microwave Measurements ◽  
Rotational Constants ◽  
Infra Red ◽  
Vibration Rotation

The infra-red absorption of nitrous oxide gas near 4·5 μ has been re-investigated using high resolving power. The rotational fine structure has been split up and shown to involve two vibrational transitions, one due to absorption of a fundamental from the ground state, and the other to a π → π transition from an excited vibrational level. The transitions have been analyzed theoretically and rotational constants obtained. The results serve to emphasize the importance of using more precise wave-length standards for infra-red measurements than have been used hitherto, if the rotational constants are to be obtained with accuracy com­parable to that achieved by microwave measurements. Excellent agreement with the latter has now been found.

Rotational analysis of bands of the 3400 Å system of disulphur monoxide (S2O)

1977 ◽  
Vol 55 (21) ◽  
pp. 1858-1867 ◽  
Author(s):  
K-E. J. Hallin ◽  
A. J. Merer ◽  
D. J. Milton
Keyword(s):  
Electronic Transition ◽  
Flow System ◽  
Type A ◽  
High Dispersion ◽  
Rotational Analysis ◽  
State Structure ◽  
Intensity Pattern ◽  
Rotational Constants ◽  
Long Wavelength

S2O has been prepared in a flow system, and various bands at the long wavelength end of the 3400 Å electronic transition photographed in absorption at high dispersion. Rotational analysis of the bands at 3235 and 3278 Å has shown that the bands are type A–B hybrids, with the type A component accounting for nearly all the observed structure. The electronic transition is therefore 1A′–1A′ (ππ*). The rotational constants imply the upper state structure r(S—S) = 2.14 Å, [Formula: see text], with r(S—O) = 1.50 Å (assumed).The vibrational intensity pattern is found to be in agreement with this structure if the electronic origin is placed at 29 696 cm−1 (3367 Å).

Rotational band contours in electronic spectra of large asymmetric top molecules: the 2750 Å system of phenol

1968 ◽  
Vol 307 (1488) ◽  
pp. 97-110 ◽  
Keyword(s):  
Excited State ◽  
Rotational Band ◽  
Point Group ◽  
Resolving Power ◽  
Hydroxyl Group ◽  
Rotational Constants ◽  
Selection Rules ◽  
Electronically Excited ◽  
Band Contour ◽  
Characteristic Features

The rotational band contour of the 0–0 band of phenol at 2750 Å has been recorded experimentally with a resolving power of 300000. The contour contains many characteristic features of which a series dependent on K a has been used to obtain trial sets of rotational constants A', B' and C' in the electronically excited state. The excited state was assumed to be planar. These data together with rotational selection rules were used in an asymmetric rotor band contour computer program and the rotational constants varied until the com­puted contour matched the observed. The contours were matched only by using type B selection rules. The electronic assignment is therefore 1 B 2 – 1 A 1 (using the C 2 v point group) and the excited state rotational constants are : A ' = 0·1773 ± 0·0002 cm -1 ; B ' = 0·08751 ± 0·00006 cm -1 ; C ' = 0·05859 ± 0·00001 cm -1 . These constants reflect an appreciable interaction of the hydroxyl group with the ring in the excited state whereas microwave data have shown very little interaction in the ground state. In particular, there is a slight overall contraction of the molecule along the long in-plane inertial axis from the ground to the excited state in contrast to an expected expansion if there were no hydroxyl group interaction. The origin of the 2750 Å 0–0 band is at 36 348·7 ± 0·2 cm -1 .

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

Etude du système A–X de PD2

1976 ◽  
Vol 54 (13) ◽  
pp. 1375-1382 ◽  
Author(s):  
M. Vervloet ◽  
J. M. Berthou
Keyword(s):  
Experimental Data ◽  
Excited State ◽  
Ground State ◽  
The Other ◽  
Good Precision ◽  
Rotational Analysis ◽  
Rotational Constants ◽  
Other Hand

The rotational analysis of the ν′2 ← 0 bands of the A–X system of PD2 has been done for ν′2 = 1 to 10. The set of the 1034 difference combinations has permitted us to determine with good precision the rotational constants of the ν″2 = 0 level of the ground state. A comparison with the corresponding constants of PH2 has shown that the application of isotopic relations to the rotational constants leads to a very good approximation in the prevision of these constants.The excited state levels are marked by large amplitudes and the Renner effect. The BDD model already applied to PH2 fits very well with the PD2 experimental data. On the other hand, although localized perturbations are less numerous in the PD2 spectrum, the presence of some intense non-identified lines suggests that interactions between higher levels of the X(2B1) state and the first levels of the A(2A1) state are to be expected.[Journal translation]

Fine structure of Tetratrichomonas limacis (Dujardin)

1972 ◽  
Vol 50 (5) ◽  
pp. 695-701 ◽  
Author(s):  
A. S. M. Saleuddin
Keyword(s):  
Fine Structure ◽  
Type A ◽  
Spatial Relationships ◽  
Type B ◽  
Digestive Cells ◽  
Otala Lactea

The fine structure of a trichomonad parasite, Tetratrichomonas limacis, which lives in the hepatopancreas of Otala lactea (Gastropoda) has been described. This flagellate has four anterior flagella and a recurrent flagellum. The structural and spatial relationships of the kinetosomal apparatus have been studied. All kinetosomes show cartwheel-like arrangement. There are two parabasal filaments of type A. The costa is of type B but has a periodicity of 600–800 Å. The undulating membrane is fairly well developed and the recurrent flagellum is closely associated with it. Internalization of flagella is seen in a few cases. A small periflagellar canal is present. Occasionally this trichomonad will extend pseudopods on to the secretory surface of the digestive cells of the hepatopancreas of Otala lactea.

High resolution study of the 5515 Å band of s-tetrazine

1969 ◽  
Vol 47 (2) ◽  
pp. 233-236 ◽  
Author(s):  
John M. Brown
Keyword(s):  
Fine Structure ◽  
High Resolution ◽  
Rotational Constant ◽  
Rotational Structure ◽  
Type C ◽  
Asymmetric Top ◽  
Low K ◽  
Resolution Study

A high resolution study of the type C(0–0) band of s-tetrazine, C2H2N4, at 5515 Å has revealed regular fine structure in the central qQ branches. The nature of this fine structure is explained using a formula appropriate to high J, low Ka asymmetric top levels and it is shown to be dependent on the change in the rotational constant C between the two states involved. It is suggested that such rotational structure should occur quite frequently in type C bands of larger molecules.

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