Phosphorescence resonance

It is relatively easy to decide which vibronic bands have a common origin. This is accomplished by observing the phosphorescence intensity change of each band upon microwave saturation at a frequency that corresponds to transitions between rz and tx. This is known as phosphorescence-microwave double resonance (PMDR) spectroscopy. These frequencies for 2,3-dichloroquinoxaline are given in Table 6.3. 

Phosphorescence microwave multiple resonance studies are likely to grow in importance in the next ten years as more systems are studied. 

Nuclear magnetic resonance spectroscopy is a technique that, based on the magnetic properties of nuclei, reveals information on the position of specific atoms within molecules. Other spectroscopic methods are based on the detection of fluorescence and phosphorescence (forms of light emission due to the selective excitation of atoms by previously absorbed electromagnetic radiation, rather than to the temperature of the emitter) to unveil information about the nature and the relative amount specific atoms in matter. 

De Groot, M.S. and Van der Waals, J.H. 1960. Paramagnetic resonance in phosphorescent aromatic hydrocarbons. II Determination of zero-field splitting from solution spectra. Molecular Physics 3 190-200. 

In these sensors, the intrinsic absorption of the analyte is measured directly. No indicator chemistry is involved. Thus, it is more a kind of remote spectroscopy, except that the instrument comes to the sample (rather than the sample to the instrument or cuvette). Numerous geometries have been designed for plain fiber chemical sensors, all kinds of spectroscopies (from IR to mid-IR and visible to the UV from Raman to light scatter, and from fluorescence and phosphorescence intensity to the respective decay times) have been exploited, and more sophisticated methods including evanescent wave spectroscopy and surface plasmon resonance have been applied. 

In the case of horse liver alcohol dehydrogenase, a homodimeric enzyme, Subramanian et al.(202) used the relative phosphorescence of tyrosine and tryptophan to examine the effects of various ternary complexes known to selectively quench the fluorescence of the tryptophans of each subunit. One proposed quenching mechanism is the formation of a ground-state tyrosinate in a ternary complex at neutral pH.(201) This tyrosinate, by being a resonance... 

J. Zuclich, D. Schweitzer, and A. H. Maki, Optically detected magnetic resonance of the tryptophan phosphorescent state in proteins, Photochem. Photobiol. 18, 161-168 (1973). 

T.-T. Co, J. Hoover, and A. H. Maki, Dynamics of the tyrosine triplet state from magnetic resonance saturated phosphorescence decay measurements, Chem. Phys. Lett. 27, 5-9 (1974). 

K. L. Bell and H. C. Brenner, Phosphorescence and optically detected magnetic resonance study of the tryptophan residue in human serum albumin, Biochemistry 21, 799-804 (1982). 

W. C. Galley, Heterogeneity in protein emission spectra, in Concepts of Biochemical Fluorescence Vol. 2 (R. F. Chen and H. Edelhoch, eds.), pp. 409-439, Marcel Dekker, New York (1976).32. S.-Y. Mao and A. H. Maki, Comparative phosphorescence and optically detected magnetic resonance studies of fatty acid binding to serum albumin, Biochemistry 26, 3576-3582 (1987). 

M. V. Hershberger, A. H. Maki, and W. C. Galley, Phosphorescence and optically detected magnetic resonance studies of a class of anomalous tryptophan residues in globular proteins, Biochemistry 19, 2204—2209 (1980). 

The new techniques of phosphorescence-microwave multiplet resonance spectroscopy with optical detection have been reviewed by El-Sayed and Kwiram Such exciting experiments as the optical detection on electron-nuclear double resonance (ENDOR) and of electron-electron double resonance (EEDOR) in zero magnetic field have been achieved, and it is certain that much detailed knowledge concerning the phosphorescent states will evolve from this field. 

El-Sayed, M. A. Phosphorescence-microwave multiple resonance spectroscopy. In MTP International Review of Science, Physical Chemistry Series One, Vol. 3. 

A number of cyano-bridged complexes are included here even though they strictly do not fall in the general family-type defined for the section. The syntheses and photophysical properties of [(NC)(bpy)2Ru(/r-NC)Cr(CN)5] and [(NC)5Cr(Ai-CI Ru(bpy)2(M-NC)Cr(CN)5] have been described. Absorption of visible light by the Ru(bpy)2 unit results in phosphorescence from the Cr(CN)g luminophore, and the results evidence fast intramolecular exchange energy transfer from the MLCT state of the Ru(bpy)2 chromophore to the doublet state of the Cr -based unit. Time-resolved resonance Raman and transient UV-vis absorption spectroscopies have been employed to investigate the MLCT excited states of [(NC)(bpy)2Ru(//-CN)Ru (bpy)2(CN)], [(NC)(bpy)2Ru(//-CN)Ru(phen)2(CN)]+, [(NC)(phen)2Ru(//-CN)Ru (bpy)2(CN)]+, [(NC)(bpy)2... 

Phosphorescence and Delayed Fluorescence from Solutions (Parker). . . Phosphorescence-Microwave Multiple Resonance Spectroscopy... 

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