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 .

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.

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]

ROTATIONAL ANALYSIS OF THE β BANDS OF PHOSPHORUS MONOXIDE

1959 ◽  
Vol 37 (2) ◽  
pp. 136-143 ◽  
Author(s):  
Nand Lal Singh
Keyword(s):  
Ground State ◽  
Band System ◽  
Electronic States ◽  
Rotational Analysis ◽  
Rotational Constants ◽  
Fine Structures ◽  
Π State

The fine structures of three of the β bands of PO which occur near 3200 Å have been analyzed. The analysis shows that the upper state of this band system is a 2Σ and not a 2Π state as previously believed. The rotational constants of both electronic states have been determined and it is found that the ground state constants, previously determined from the γ bands, are incorrect.

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 analysis of a 2 A 1 - 2 B 1 electronic band system of the AsH 2 and AsD 2 radicals

1968 ◽  
Vol 305 (1481) ◽  
pp. 271-290 ◽  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Flash Photolysis ◽  
Band System ◽  
Valence Angle ◽  
Electronic Transitions ◽  
Doublet State ◽  
Electronic Band ◽  
Asymmetric Rotor ◽  
Asymmetric Top

Two new band systems have been observed in absorption following flash photolysis of AsH 3 and AsD 3 , and are assigned to 2 A 1 - 2 B 1 electronic transitions of AsH 2 and AsD 2 . The origins of both systems are at 19905 cm -1 . The bands have the complex rotational structure associated with an asymmetric rotor. Rotational analyses have been carried out for three bands of the AsH 2 spectrum, leading to the following molecular parameters: ground state, r" 0 = 1.518 Å valence angle = 90° 44'; excited state, r' 0 = 1.48 Å, valence angle = 123° 0'. The parameters associated with rotation about the a inertial axis increase rapidly with increase in v' 2 . The spectrum shows doublet splittings of up to 41 cm -1 , and the excited state furnishes the first example of a doublet state of an asymmetric top molecule which shows substantial departures from Hund’s case ( b ).

scholarly journals Internal Rotation of the Methyl Group in the Electronically Excited State: o- and m-Toluidine

1987 ◽  
Vol 7 (2-4) ◽  
pp. 197-212 ◽  
Author(s):  
Katsuhiko Okuyama ◽  
Naohiko Mikami ◽  
Mitsuo Ito
Keyword(s):  
Excited State ◽  
Internal Rotation ◽  
Barrier Height ◽  
Ground State ◽  
Electronic Excitation ◽  
Vibrational Analysis ◽  
Fluorescence Excitation ◽  
Close Relationship ◽  
Electronically Excited ◽  
Dispersed Fluorescence

The fluorescence excitation and dispersed fluorescence spectra of jet-cooled o- and m-toluidine were observed. Vibrational analysis of the spectra provided us with the potentials for the internal rotation of the CH3 group in both ground and excited states. In o-toluidine, a large potential barrier to the internal rotation in the ground state is practically removed in the excited state. On the other hand, a nearly free internal rotation of the CH3 group in the ground state of m-toluidine gains a large barrier by the electronic excitation. The great change in the barrier height upon the electronic excitation is more remarkable than that found for fluorotoluene. A close relationship between the barrier height and the π electron density at the ring carbon atom was found, indicating the hyperconjugation as the origin of the barrier height in the absence of steric hindrance.

The electronic spectrum of F2

1976 ◽  
Vol 54 (13) ◽  
pp. 1343-1359 ◽  
Author(s):  
E. A. Colbourn ◽  
M. Dagenais ◽  
A. E. Douglas ◽  
J. W. Raymonda
Keyword(s):  
Absorption Spectrum ◽  
Ground State ◽  
Band System ◽  
Rydberg States ◽  
Rotational Analysis ◽  
Interaction Energies ◽  
Rydberg Series ◽  
Rotational Constants ◽  
Vibrational Levels ◽  
Ionic States

The absorption spectrum of F2 in the 780–1020 Å range has been photographed at sufficient resolution to allow a rotational analysis of many bands. A large number of vibrational levels of three ionic states have been observed and their rotational constants determined. Many perturbations in the rotational structure caused by the interaction between the three states have been investigated and the interaction energies determined. The rotational and vibrational structures of a few Rydberg states have also been analyzed in detail but no Rydberg series have been identified. The difficulties in assigning the observed states are discussed. A 1Σu+ – X1Σg+ emission band system has been observed in the 1100 Å region. An analysis of the bands of this system has allowed us to determine the term values and rotational constants of all the vibrational levels of the ground state with ν ≤ 22. The dissociation energy, D0(F2), is found to be greater than 12 830 and is estimated to be 12 920 ± 50 cm−1.

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.

Etude à basse température dans l'infrarouge proche du dimère (NO)2

1984 ◽  
Vol 62 (4) ◽  
pp. 322-329 ◽  
Author(s):  
V. Menoux ◽  
R. Le Doucen ◽  
C. Haeusler ◽  
J. C. Deroche
Keyword(s):  
Excited State ◽  
Gas Phase ◽  
Ground State ◽  
Near Infrared ◽  
Heat Of Formation ◽  
Wave Number ◽  
Vibrational Modes ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Absorption Intensity

The spectrum of the dimer (NO)2 in the gas phase has been studied in the near infrared at temperatures between 118 and 138 K. More specifically, the measure of absorption intensity of the ν4 and ν1 + ν4 bands has yielded the heat of formation of the dimer, −2.25 kcal/mol at 128 K, and revealed the influence of the low vibrational modes on this measure. The observation of the ν4 – ν6, difference band has yielded the wave number value of the ν6, fundamental band, forbidden in the infrared. The rotational constants of the vibrationally excited state were found to be larger than the ground state rotational constants, this result being very unusual.

Spectrum of AsS. I. Analysis of the A′2Π3/2–X2Π3/2 Band System

1971 ◽  
Vol 49 (10) ◽  
pp. 1249-1254 ◽  
Author(s):  
Midori Shimauchi
Keyword(s):  
High Resolution ◽  
Emission Spectrum ◽  
Ground State ◽  
Band System ◽  
Vibrational Analysis ◽  
Quartz Tube ◽  
Rotational Analysis ◽  
Vibrational Constants

The emission spectrum of the AsS radical, excited in a quartz tube by a 2450 MHz oscillator, was photographed on a high resolution spectrograph from 2450 to 6900 Å. Seven bands around 6000 Å showing clear rotational structures were chosen for the first rotational analysis of the AsS spectrum. The bands were found to arise from a 2Π3/2–2Π3/2 transition. The rotational and vibrational constants of the two states derived from the present work are consistent with the previous vibrational analysis of the A′2Π3/2–X2Π3/2 system. The constants of the upper doublet component of the ground state, X2Π3/2, are ωe = 562.40 cm−1, ωexe = 2.02 cm−1, re = 2.0216 Å; the constants of the A′2Π3/2 state are ΔG′(1/2) = 403.37 cm−1, ν0,0 = 18 621.21 cm−1, re = 2.2500 Å.

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