B.J. Shetty

Rotational analysis of the E1Σ+-X1Σ+ bands of SiS

Abstract Rotational analyses of 21 bands lying in the region 4400–6600 A and belonging to the E1Σ+-X1Σ+ system of SiS have been carried out. These bands arise from transitions involving vibrational levels v = 7, 8, and 14–19 in the E state and the vibrational levels v = 34, 35, and 47–54 in the X1Σ+ state. By combining the present band origin data with those of previous workers in a least-squares fit, the following set of vibrational constants has been obtained: State T e ω e ω e x e ω e y e ω e z e E 1 Σ + 41914.3(3) 406.76(22) 1.90(4) −0.005(2) −0.000038(2) X 1 Σ + 0 749.50(10) 2.566(4) 0.00033(5) — Similarly, by fitting the rotational constants from the present as well as the previous microwave and optical data with appropriate weightages, the following set of equilibrium rotational constants has been obtained: State B e α e γ e δ e E 1 Σ + 0.22174(11) 0.00167(5) 0.000031(5) 0.0000021(2) X 1 Σ + 0.303528 0.001443(3) −0.00000269(8) −0.0000000528(7) Rotational perturbations have been observed in the v = 16, 18, and 19 vibrational levels of the E1Σ+ state for the first time.

The vibrational and rotational analysis of the E1Σ+-X1Σ+ system of SiSe

Abstract By exciting the spectrum of SiSe in a microwave discharge we have obtained, in addition to all of its three known band systems, namely, E 1 Σ + - X 1 Σ + (2450–2770 A), A 1 Π- X 1 Σ + (2900–3900 A), and a 3 Π- X 1 Σ + (3900–4300 A), a large number of new bands in the region 4000–6000 A. From a detailed vibrational analysis we have shown that the new bands also belong to the E 1 Σ + - X 1 Σ + system and arise out of transitions from 0 ≤ v ≤ 13 levels of the E 1 Σ + state to the 25 ≤ v ≤ 52 levels of the X 1 Σ + state. We have carried out the vibrational isotope shift studies of 28 Si 78 Se and 28 Si 80 Se which showed that the vibrational numbering of the new bands as well as that of the bands in the region 2450–2770 A is correct. From a least-squares fitting of the bandheads the vibrational constants have been obtained. Rotational analysis of eight bands, namely, 946, 945, 845, 844, 843, 743, 70, and 80 has been carried out which has further confirmed the above assignments. A simultaneous least-squares fit of all the rotational lines of the eight bands together with the three microwave transitions previously observed by Hoeft in the v = 0 level of the ground state ( J = 1 ← 0 at 11 489.44 MHz, J = 2 ← 1 at 22 978.69 MHz, and J = 3 ← 2 at 34 468.17 MHz) has been carried out. From this fit accurate rotational constants are obtained for the electronic states involved in the transition.

Rotational analysis of the a3Π-X1Σ+ bands of GaD

Abstract A new method of producing strong and clean emission spectra of the gallium hydride/deuteride molecule has been developed. Five bands belonging to the gallium deuteride molecule (GaD) have been photographed under high resolution. The rotational analyses of the bands lying at 5669.14 A (0-0) and 5675.10 A (1-1) in the a 3 Π 1 - X 1 Σ + transition, 5761.0 A (0-0) and 5766.20 A (1-1) in the a 3 Π 0 + - X 1 Σ + transition, and 5760.85 A (0-0) in the a 3 Π 0 − - X 1 Σ + transition have been performed. Accurate rotational constants ( B , D ) have been determined for the X 1 Σ + , a 3 Π 0 ± and a 3 Π 1 ± states. The Λ doubling in the a 3 Π 0 ( v = 0) and a 3 Π 1 ( v = 0 and 1) states are obtained.

Franck-Condon factors and r-centroids for the E1Σ+−X1Σ+ bands of SiS and SiSe

Abstract By using the computer program TRAPRB developed by Jarmain and McCallum, Franck-Condon factors and r-centroids have been calculated for the E 1 Σ + − X 1 Σ + bands of the SiS and SiSe radicals. Intensities of these bands have been visually estimated from the emission spectra photographed on a 3.4 m Ebert grating spectrograph (5 A/mm). A comparison of the Franck-Condon factors with these estimated intensities shows reasonable agreement.