Investigations of some diatomic molecules : the hydrides of selenium, antimony and silicon and the platinum oxide

Sammanfattning: This thesis is an extension and a summary of investigations on the electronic spectra of gaseous SeH/D, SbH/D, PtO and to some minor extent also of gaseous SiH. Rotational analyses are performed on each molecule.SeH/D molecules were generated in photolysis reactions using 12 µs long light flashes. The vacuum ultraviolet spectra were recorded in a 3 m vacuum spectrograph by means of a rapid discharge background lamp, triggered by the photolysis pulse. The ground state constants are calculated and are found to be in reasonable agreement with those determined by other means. Most upper states are believed to be Rydberg states and are tentatively arranged into two different Rydberg series. In addition to similar flash photolysis experiments SbH/D molecules were generated in electric flash discharge experiments with pulse lengths shorter than 1 µs. Spectra were recorded in the same spectrograph using the same type of background lamp as in the SeH/D experiments. The ground state is reinvestigated. A number of new upper electronic states are analyzed and assigned. They are believed to be Rydberg states although they are not arranged into series.The emission spectrum of SiH was recorded around 4100 Å using a high resolution spectrograph. The band spectrum of the A 2Δ - X 2TT transition was carefully measured and the rotational constants of upper and lower states are calculated in a direct approach way. Special attention is paid to determination of the ground state Λ-type doubling. Emission spectra of PtO from 3800 Å to 8900 Å were recorded in high resolution, thirteen new case c states are analyzed. The two lowest PtO states are believed to constitute a 3∑- state. The splitting of this 3∑- state is in good agreement with what is expected from the influence of the distant A 1∑+state if the molecular spin-orbit coupling constant is around -2000 cm-1. This means that (Pt5dπ)2 is a plausible origin of the lowest state.Finally a short review section deals with low-lying configurations of all known diatomic transition metal oxides and hydrides.