Albrecht theory

The term ll scattering (equation 7) from vibronic activity in allowed electronic transitions mainly results in fundamental transitions of non-totally symmetric vibrations. This term corresponds to the B and C terms of the Albrecht theory. ... 

The resonance-Raman excitation profile of carotenoid in the 2 Ag state can be explained by the A term of the Albrecht theory (Tang and Albrecht, 1970) that is applicable to the totally-symmetric(ag-type) modes when the electronic transition dipole is not completely zero (Sashima et al., 1998a). The results lead us to the conclusion that the observed... 

The chromophoric character of the conjugated bonds leads to a similar resonance enhancement for the Raman lines in the various systems. This is shown in Fig.lO. The similarity of the experimental results allows to interprete the data in terms of the Albrecht theory for conjugated systems . The resonance cross-section for poly(acetylene) is for the long chain part of the Raman line. The observed resonance enhancement for C 0 is more than a factor of 50. In this case the lowest two allowed optical transitions hu to t g and hg+Qg to [Pg.364]

Figure 10. Resonance cross-section for the bond alternation mode Raman line in poly(acetylene) (PA), potassium reduced carbyne (CA) and fuUerene (Ceo)- The cross-section is in arbitrary units. The full drawn lines are as calculated from the A-term in the Albrecht theory. The dashed line is a guide line for the eye.

The transition moment derivative related to the normal coordinate, r, can be treated as another adjustable parameter to obtain the best agreement between theoretical and experimental fits. In the Albrecht theory, it is given a more detailed meaning to present in the B term when we use the... 

However, the calculation of resonance Raman profiles by file direct use of the KHD equation is so difficult in the case of polyatomic molecules due to the sum of a great number of intermediate states, even using the A term or using the great order terms B, C, and D of Albrecht theory. In a polyatomic molecule with N atoms, there will be 3N—6 normal modes, and the Iv) term is an abbreviate notation used for the vibrational quantum number set of all modes, that is, IV1V2V3.. Each possible combination of the v, vibra-... 

Melinger J S and Albrecht A C 1986 Theory of time- and frequency-resolved resonance secondary radiation from a three-level system J. Chem. Phys. 84 1247-58... 

Tang J and Albrecht A C 1970 Developments in the theories of vibrational Raman intensities Raman Spectroscopy Theory and Practice vol 2, ed H A Szymanski (New York Plenum) pp 33-68... 

Albrecht A C, Clark R J H, Oprescu D, Owens S J R and Svensen C 1994 Overtone resonance Raman scattering beyond the Condon approximation transform theory and vibronic properties J. Chem. Phys. 101 1890-903... 

Dugan M A and Albrecht A C 1991 Radiation-matter oscillations and spectral line narrowing in field-correlated four-wave mixing I theory Rhys. Rev. A 43 3877-921... 

Ulness D J and Albrecht A C 1997 A theory of time resolved coherent Raman scattering with spectrally tailored noisy light J. Raman Spectrosc. 28 571-8... 

Ulness D J, Kirkwood J C, Stimson M J and Albrecht A C 1997 Theory of coherent Raman scattering with... 

Finally attention is drawn to a germinal paper on the application of group theory to problems concerning the nature of crystals which was published in 1929 by another Nobel Prize winner, the German physicist Hans Albrecht Bethe (1906-). 

An exact asymptotic value of p [X) is still unknown, but it is expected to be somewhere between 1.55 and 1.72, the upper limit being suggested by Stockmayer and Albrecht s perturbation theory of the friction constant [239). 

Vibrational analysis of the benzene phosphorescence bands indicates that the radiative activity is induced predominantly by e2g vibrations [155, 156]. A weak but observable activity of b2g vibrations has also been found [156, 155, 157]. By introducing spin-orbit- and vibronic coupling through second order perturbation theory Albrecht [158] showed that the vibronic interaction within the triplet manifold is responsible for the larger part of the phosphorescence intensity. This also follows from comparison of the vibrational structure in phosphorescence and fluorescence spectra [159]. The benzene phosphorescence spectrum in rigid glasses [155] reveals a dominant vibronic activity of... 

The dispersion phenomenon has been quantitatively approached by three models. Initially, Albrecht s theory (Tang and Albrecht, 1970) was applied to the finite segments of the polymer. Then, in the case of materials such as trans-Vk, use of an empirical distribution function P N) for the conjugation length made it possible to exactly reproduce the line shapes and line intensities resulting from excitation with different laser lines ... 

Tang J, Albrecht AC (1970) Developments in the theories of vibrational Raman intensities. In Szymanski HA (ed) Raman Spectroscopy. Plenum Press, New York London, p 33 Tannor DJ, Heller EJ (1982) J Chem Phys 77 202 Taraschi T, Mendelsohn R (1980) Proc Natl Acad Sci USA 77 2362... 

The measurements of the second virial coefficients of chain pol3mier solutions have proved that the above theoretical conclusions are correct 33). Because of this success, attempts to refine the theory taking m ly the excluded volume effect of the segments into consideration have been made by Oeofino and Fkory, Albrecht, Yamakawa, Yama-KAWA and Kurata, Casrsassa (34) and others. However, it is perhaps... 

There have been extensive theoretical treatments of resonant and preresonant Raman scattering, which reveal the important factors affecting the magnitude of p. However, it is difficult to theoretically predict p from molecular structure, and the theory is normally used to predict laser frequency dependence and deduce the relationship between resonance Raman spectra and molecular structure. Albrecht and Hutley (22) derived an expression for the laser frequency dependence of the cross section ... 

Morell, J.A., Albrecht, A.C. Second-order hyperpolarizability of p-nitroaniline calculated from perturbation theory based expression using CNDO/S generated electronic states. Chem. Phys. Lett. 64, 46-50 (1979)... 

DL Dexter (1953) A theory of sensitized luminescence in solids. J Chem Phys 21 836-860 T Gillbro and RJ Cogdell (1989) Carotenoid fluorescence. Chem Phys Lett 158 312-316 T Katoh, U Nagashima and M Mimuro (1991) Fluorescence properties of the allenic carotenoid fucoxanthin Implication for energy transfer in photosynthetic pigment systems. Photosynthesis Res 27 221-226 AP Shreve, JK Trautman, TG Owens and AC Albrecht (1991) A femtosecond study of electronic state dynamics of fucoxanthin and implication for photosynthetic carotenoid-to-chlorophyll energy transfer mechanisms. Chem Phys 154 171-178... 

On the theoretical side, simple cosmological models with a varying fine structure constant have now been developed (see, for example, Sandvik et al., 2002 Barrow etal., 2002b). They share some properties with Kaluza-Klein-type models in which a varies at the same rate as the extra dimensions of space (see, for example, Damour and Polyakov, 1994) and with varying-speed-of-light theories (see, for example, Albrecht and Magueijo, 1999 Barrow and Magueijo, 2000). 

Gould [32] ascribes the first usage of evolution in this context to Albrecht von Haller. I have been unable to corroborate this source, instead finding a tentative suggestion from his contemporary. Bonnet, that evolution describes the process of organic change over time [37]. For our purposes, the discrepancy is inconsequential both presented preformationist theories of evolution at about the same point in history. 

Albrecht AC (1961) On the theory ofRaman intensities. J Chem Phys 34 1476-1484... 

---