Absorption spectrum of SiH in the vacuum ultraviolet

1969 ◽  
Vol 47 (18) ◽  
pp. 1889-1897 ◽  
Author(s):  
G. Herzberg ◽  
A. Lagerqvist ◽  
B. J. McKenzie

A new electronic transition of SiH has been observed in absorption near 1907 Å in flash discharges through mixtures of SiH4 and H2. The rotational analysis shows this transition to be of the type 2Σ+−2Π. The corresponding transition of SiD has also been observed and analyzed. The D2Δ−X2Π transition near 2058 Å which was observed and analyzed by Verma in SiD has been measured here for SiH, where the lines are much broader on account of predissociation. The predissociation phenomena in SiH and SiD and the electron configurations are briefly discussed, and the presently known molecular constants of these molecules are summarized.


1973 ◽  
Vol 51 (20) ◽  
pp. 2184-2188 ◽  
Author(s):  
J. C. D. Brand ◽  
J. L. Hardwick ◽  
R. J. Pirkle ◽  
C. J. Seliskar

A krypton ion laser operating at 6470 Å excites strong resonance fluorescence in nitrogen dioxide gas. The fluorescence bands have "parallel" structure (ΔK = 0) and are assigned to the electronically allowed subsystem of a 2B2–2A1 electronic transition. A partial rotational analysis is given for the upper state of the fluorescence bands, and their relationship to the absorption spectrum in the region 6000–11 500 Å is discussed.



The spectra of the diatomic hydrides of lithium, sodium and potassium have been studied both in absorption and in emission by several authors, LiH by Nakamura (1930, 1931) and Crawford and Jorgensen (1935), NaH by Hori (1930, 1931) and Olsson (1935), KH by Almy and Hause (1932) and Hori (1933), and recently Almy and Rassweiler (1938) have published details of the absorption spectrum of caesium hydride. All these hydrides show spectra of the “ many-line” type consisting of numerous overlapping bands with open rotational structure and no obvious heads. A rotational analysis shows that they all have the same type of electronic transition, 1Σ → 1Σ ,and are very strongly degraded towards the red. These spectra are all anomalous in that the frequency, ω´ v , and the rotational constant, B'v,increase at first with increasing initial vibrational quantum numbe v `.



1981 ◽  
Vol 59 (3) ◽  
pp. 506-517 ◽  
Author(s):  
P. S. Neudorfl ◽  
R. A. Back ◽  
A. E. Douglas

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.



1972 ◽  
Vol 50 (19) ◽  
pp. 2265-2276 ◽  
Author(s):  
J. M. Berthou ◽  
B. Pascat ◽  
H. Guenebaut ◽  
D. A. Ramsay

Rotational analyses have been carried out for the 0ν′20–000 bands of the [Formula: see text] electronic transition of PH2 with ν′2 = 1–8. Approximately 1000 lines have been assigned. The earlier analysis of the 000–000 band has been extended and improved molecular constants obtained. The Hamiltonian used for this band does not fit the excited state levels with [Formula: see text]. Term values are therefore given for all observed levels. Empirical formulas are presented which give approximate fits to the higher levels. Numerous rotational perturbations are found in the excited state. Perturbations up to 0.6 cm−1 are also found in the 000 level of the excited state. These latter perturbations can only be caused by the higher vibrational levels of the ground state.



1965 ◽  
Vol 43 (1) ◽  
pp. 74-81 ◽  
Author(s):  
A. E. Douglas ◽  
K. P. Huber

An investigation of the absorption spectra of both 14NO2 and 15NO2 has revealed a long progression of red-degraded bands in the region 3 700–4 600 Å. The rotational analysis shows that these bands are the Ka = 0 ← 1 subbands of the electronic transition 2B1 ← 2A1. The interpretation of the bands is discussed, and a few remarks concerning the onset of predissociation at 3 979 Å are added.



A new absorption spectrum has been found in the flash photolysis of H 3 BCO which, from its structure and the observed isotope shifts can be unambiguously assigned to the free BH 2 radical. The spectrum represents a transition similar to those previously observed in NH 2 and CH 2 . The molecule is linear in the excited state but bent (with an angle of 131°) in the ground state. Molecular constants and geometrical data are evaluated. The electronic transition is 2 B 1 ( II u ) – 2 A 1 and fits well with expectation from the Walsh diagram for X H 2 molecules.



1962 ◽  
Vol 40 (4) ◽  
pp. 412-422 ◽  
Author(s):  
P. Ramakoteswara Rao ◽  
R. K. Asundi ◽  
J. K. Brody

The F–X band system of Cu65Cl35 extending from 3700 to 4200 Å has been photographed in emission under high resolution. Rotational analysis of the (3,0), (2,0), (1,0), (0,0), (0,1), and (0,2) bands of the system has been made. The electronic transition involved is found to be 1Π–1Σ. The Λ-type doubling in the 1Π state is negligible. The principal molecular constants obtained are as follows (cm−1 units)[Formula: see text]



1976 ◽  
Vol 54 (10) ◽  
pp. 1043-1052 ◽  
Author(s):  
J. A. Coxon ◽  
W. E. Jones ◽  
E. G. Skolnik

Five bands of the 0–ν″ progression (5 ≤ ν″ ≤ 9) of the A2Πi–X2Πi system of 35ClO have been rotationally analysed. The results have been combined with data from the absorption spectrum of ClO, and new molecular constants are reported. The variation of spin–orbit coupling with internuclear separation has been determined for both states.



Author(s):  
Paul Brint ◽  
Jean-Patrick Connerade ◽  
Pericles Tsekeris ◽  
Agisilaos Bolovinos ◽  
Aslam Baig


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