I. Dubois

New analysis of the A3Πi-X3Πi transition of BN

Abstract A new analysis of the A-X transition of BN, based on well-resolved spectra, has yielded B values which differ significantly from those of Douglas and Herzberg [Canad. J. Res. A. 18, 179–185 (1940)]. The new constants, B0′ = 1.449 cm−1 and B0″ = 1.548 cm−1 are in very good agreement with ab initio calculations of Karna and Grein (to be published).

The absorption spectrum of the H2CSi radical

Abstract A well-resolved absorption band system, observed between 3400 and 3100 A after a flash discharge through methylsilane, is ascribed to the free H 2 CSi radical. Isotopic species D 2 CSi and HDCSi are also observed. The transition is shown to be of the type 1 B 2 - 1 A 1 , and rotational constants are given for the lower and the upper electronic states.

The singlet bands of BN

The weak bands, tentatively attributed by Douglas and Herzberg (1940) to singlet bands of BN have been analysed and attributed to two distinct transitions of this radical: the c1 Sigma +-a1 Sigma + and the c1 Sigma +-b1 Pi transitions. Electron configurations of the new states are discussed.

Rotational analysis of the 000-000 and 010-000 bands of SiC2

Abstract High-resolution absorption spectra of SiC 2 have been observed in a flash discharge through Si(CH 3 ) 2 and helium. The two strongest bands at 4977 and 4867 A have been fully analyzed. The rotational constants derived accurately predict the observed interstellar lines.

A new analysis of the vibration-rotation spectrum of CH from solar spectra

Abstract In the solar spectrum, CH vibration-rotation lines are excited to higher vibrational and much higher rotational quantum numbers than in any laboratory source. We have observed, for the first time, a very large number of new lines (1-0 and 2-1 up to J = 34.5, 3-2 up to J = 31.5, and even 4-3, never seen before, up to J = 24.5) on solar spectra obtained from space, with the ATMOS-SL3 instrument. A total of 558 lines have been used to derive new accurate molecular constants for the X 2 Π ground state of CH.

The electronic spectrum of CCl

The A2 Delta -X2 Pi transition of CCl has been reinvestigated and the rotational analysis has been considerably extended. Precise molecular constants have been obtained for the two states involved. A new transition (B2 Sigma +- Sigma 2 Pi ) has been observed for the first time as well as diffuse absorptions in the vacuum ultraviolet.

Rydberg states of SiF in the vacuum ultraviolet

Ten Rydberg states of SiF have been observed below 2000 AA. Five of them have not been reported before. They all have been rotationally analysed.

The a 3Πj--X1B+ transition of SiO

The spin-forbidden transition a 311r-x l2+ of Si0 has been observed in emission. The vibrational constants have been derived for the a 311r state. Furthermore, the energies of all the known triplet states relative to the xlX+ ground state have been obtained for the first time.

Rydberg states and ionization potentials of GeX, SnX, and PbX (X = F, Cl, Br, I)

Abstract Thirty-nine unattributed electronic states of group IV monohalides have been interpreted in terms of Rydberg configurations. Ionization potential and quantum defects have been derived.

Excited vibrational levels of the ground state of B2: The A3Σu−-X3Σg− transition

Abstract A better description of the electronic ground state of 11B2 has been obtained from the rotational analysis of four 0-v″ bands (v″ = 12 to 15) of the A3Σu−-X3Σg−.