Gas phase vacuum-ultraviolet (vuv) spectroscopy of small halogenated polyatomic molecules

The work carried out in this thesis is concerned with photoexcitation of small and halogenated molecules in the gas phase with vacuum-ultraviolet (VUV) radiation. For all the experiments described in this thesis, the source of radiation was from tuneable VUV radiation from a synchrotron source. The majority of the experiments used the UK national source located at Daresbury Cheshire. Fluorescence spectra were taken using the newly commissioned Wadsworth monochromator on beamline 3.1 of the Daresbury synchrotron radiation source. Dispersed florescence spectra were taken using a newly developed fluorescence apparatus incorporating a multi-channel CCD detection system. One of the objectives of this thesis is to compare the sensitivity and resolution of this new system with that of an apparatus used at the BESSY 1 synchrotron source in the 1990s. Many of the molecules studied here were chosen because previous data recorded at BESSY 1 were available for this comparison. Molecules studied include the MCl₄ series (M = C, Si and Ge) where both the VUV photoabsorption and fluorescence spectra were recorded. A new analysis of the absorption spectra is presented. Emissions are observed in MCl₂, MCl and the parent ion of SiCl₄⁺ and GeCl₄⁺. The CF₃X series (X = H, F, Cl, Br, I and SF₅) where the fluorescence spectra and some photoabsorption spectra were recorded. Emissions are observed in CF, CF₂, CF₃ and parent ion CF₄⁺, CF₃H⁺. Undispersed and dispersed fluorescence spectra of BX₃ (X = F, Cl and Br) were also recorded. Emission is now observed in BX₂, BX and parent ion BX₃⁺. Finally the fluorescence spectra of PX₃ (X = F, Cl and Br) were recorded and are presented here. Emissions are observed in PX₂, PX and parent ion PX₃⁺.

Name dc:type.qualificationname

d_ph

Level dc:type.qualificationlevel

d_ph

Grantor dc:publisher.institution

University of Birmingham

Year dc:date.issued

2007

Author dc:creator

• Ali, Sahangir

• QD Chemistry