Esmaspäeval, 27. okt. 2014. kell 16.15 toimub Physicumis (Ravila 14C), 3. korruse seminariruumis D312
Väike materjalifüüsika ja spektroskoopia seminar nr. 182
Indrek Renge Laserspektroskoopia labor, FI, LOTE, TÜ
Probing by molecules and light
Decoding the optical message a chromophore is sending out is a detective’s work.
We investigate spectral changes between the vapor and liquid phase. Solution spectra are shifted and broadened for two reasons, a displacement of energy levels and coupling to matrix phonons. Thus, four groups of phenomena can be distinguished:
- overall shift of spectral contour
- inhomogeneous broadening
- thermal shift of transitions (2nd order EPC)
- thermal broadening (1st and 2nd order EPC).
A new effect was discovered in formaldehyde HCHO, acetaldehyde CH3CHO and acetone (CH3)2CO spectra, namely a change of Franck-Condon factors for overtones. Nontrivial consequences of this finding will be discussed in detail. The London, Lorentz-Lorenz, Onsager formulas, Lennard-Jones potentials, and other insightful classical tools will be remembered, and contrasted to “modern” achievements.