Vibrating structures

Pack R T 1976 Simple theory of diffuse vibrational structure in continuous UV spectra of polyatomic molecules. I. Collinear photodissociation of symmetric triatomics J. Chem. Phys. 65 4765... 

The photoelectron spectrum of FH,is shown in figure A3.7.6 [54]. The spectrum is highly structured, showing a group of closely spaced peaks centred around 1 eV, and a smaller peak at 0.5 eV. We expect to see vibrational structure corresponding to the bound modes of the transition state perpendicular to the reaction coordinate. For this reaction with its entrance chaimel barrier, the reaction coordinate at the transition state is... 

Some other extremely iisellil spectroscopic teclmiques will only be mentioned here. Probably the most important one is spectroscopy in free jet expansions. Small molecules have often been studied by gas-phase spectroscopy where sharp rotational and vibrational structure gives detailed iufonnation about molecular... 

Often it is possible to resolve vibrational structure of electronic transitions. In this section we will briefly review the symmetry selection rules and other factors controlling the intensity of individual vibronic bands. 

Zare R N 1964 Calculation of intensity distribution in the vibrational structure of electronic transitions the B... 

Vibrational transitions accompanying an electronic transition are referred to as vibronic transitions. These vibronic transitions, with their accompanying rotational or, strictly, rovibronic transitions, give rise to bands in the spectrum, and the set of bands associated with a single electronic transition is called an electronic band system. This terminology is usually adhered to in high-resolution electronic spectroscopy but, in low-resolution work, particularly in the liquid phase, vibrational structure may not be resolved and the whole band system is often referred to as an electronic band. 

In the case of ozone, for which both the Hartley and Huggins systems are very broad showing no rotational and very little vibrational structure, the two wavelengths must be more widely separated. 

The splitting of both groups (visible and UV regions) is related to a vibrational structure of electron transitions (characteristic frequencies being... 

Benzyl derivatives of (1 6)-a-D-glucan, (l->6)-a-D-mannan, and (l-> 6)-a-D-galactan have been studied in 1,4-dioxane. These derivatives have complex and interesting c.d. spectra due to the ww transition of the chromophore with resolved vibrational structure. However, a conformational interpretation of these interesting spectra is not possible at this time. 

Excimers are often characterized by a broad emission band containing no vibrational structure, occurring at longer wavelengths than emission corresponding to the monomeric singlet state/41,87-89,71-73 ... 

Since the phosphorescence emission from (6) (68.8 kcal/mole) is very similar in energy and vibrational structure to benzophenone, and has a short lifetime (0.5 msec), it was proposed that the photorearrangement takes place via the triplet state. A Zimmerman-like mechanism is as follows for the formation of the cyclopropyl ketone (7) from dienone (6) ... 

Blasse, B. Vibrational Structure in the Luminescence Spectra of Ions in Solids. 171, 1-26... 

Increasing the initial concentration of zeaxanthin to 10 4 M, Figure 8.6b, produces a different dependence on the ethanol/water ratio. Under these initial conditions, adding water to a final ethanol/water ratio of 3 2 leads to a distinctly different absorption spectrum than that observed at lower initial concentration. The vibrational structure of the S2 state is preserved and a new absorption band characteristic of J-aggregates appears at 530 nm. When the water content was increased... 

Alper, J. S., H. Dothe, and M. A. Lowe. 1992. Scaled Quantum Mechanical Calculation of the Vibrational Structure of the Solvated Glycine Zwitterion. Chem. Phys. 161, 199-209. 

Alper, J. S., H. Dothe, and M. A. Lowe. 1992. Scaled Quantum Mechanical Calculation of the Vibrational Structure of the Solvated Glycine Zwitterion, Chem. Phys. 161, 199-209. Barron, L. D., A. R. Gargaro, L. Hecht, P. L. Polavarapu. 1991. Experimental and Ab Initio Theoretical Vibrational Roman Optical Activity of Alanine, Spectrochimica Acta 47A, 1001-1016. 

Phosphorescence spectra of DTT and DTP were measured in MeOH/EtOH glass at 77 K. DTT and DTP exhibited phosphorescence with clear vibrational structure. This finding is attributed to the rigid structure caused by the bridging group at the 3,3 positions of 2,2-bisthiophene 84. The triplet energy of DTT and DTP estimated from the 0-0 bands of the phosphorescence spectra are given in Table 9. 

The spectrum of this compound displays a structured band at 437 nm. The vibrational structure was extensively studied and assigned to vibronic levels of a 6 -> n and a 6) 8 state with activity in the Mo-Mo and Mo-0 stretching modes (49-56). The MPI photofragment spectrum following excitation at 450 nm is dominated by Mo+ and Mo0+. In contrast, excitation at 337 nm accesses a structureless band assigned to the 5 > n (carbon) transition. Photofragmentation is dominated by with a weaker Mo0 ... 

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