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The high resolution electronic spectrum of propynal

Edwards, Simon Anthony; (1991) The high resolution electronic spectrum of propynal. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

The one photon ultraviolet absorption spectra of propynal (HCCCHO) and the three deuterated compounds have been recorded under a higher resolution than has previously been reported. The spectrum arising from the ùA" ← ùA' (S₁ ← S₀ ) transition has been studied in detail and the existing vibrational analysis has been extended. Rotational analyses of many of the vibrational bands in this spectrum have been carried out. Several vibrational and rotational perturbations have been observed and for many of these coupling matrix elements have been calculated. Where possible perturbing levels have been suggested. Existing studies on the ground electronic states of these compounds have been correlated and improved values of the molecular constants have been obtained. These values have been further enhanced from rotational analyses of the origin and lower vibrational bands of the S₁ ← S₀ spectrum by weighted least squares fits to both lower and excited states. On excitation of higher vibrational levels in the S₁ state of propynal an overall broadening and diffuseness of rotational structure is observed. This has been charted throughout the spectrum and lifetimes of the levels concerned have been estimated from the linewidths. These observations are compared to previous fluorescence studies and interpreted in terms of vibrationally and rotationally dependent predissociation. The origin band of the T₁ ← S₀ transition is reported for the molecules HCCCDO and DCCCDO for the first time and partial rotational analyses are attempted. The kinetics and mechanisms of energy decay from the S₁ and T₁ states of propynal are discussed on the basis of the results of this and previous studies.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: The high resolution electronic spectrum of propynal
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Pure sciences; Ultraviolet absorption spectra
URI: https://discovery.ucl.ac.uk/id/eprint/10107037
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