Probed resonance

Tune the probe to the correct frequencies. For low y nuclei, or nuclei with very large chemical shift ranges, make sure the probe is tuned for the resonance frequency of the sample you are using, for example, the chemical shift range of ° Rh can exceed the width of the probe resonance. 

The use of STM to the identification of structurally similar molecules by probing resonant tunneling. 

Hashimoto H and Koyama Y (1989) The C=C stretching Raman lines of /3-carotene isomers in the S state as detected by pump-probe resonance Raman spectroscopy. Chem Phys Lett 154 321-325... 

Gruszecki WI, Matula M, Ko-chi N, Koyama Y and Krupa Z (1997) Cis-trans isomerization of violaxanthin in LHCII violaxanthin isomerization within the violaxanthin cycle. Biochim Biophys Acta 1319 267-274 Hashimoto H and Koyama Y (1988) Time-resolved Raman spectroscopy of triplet y3-carotene produced from all-trans, 7-is, 13-cis and 15-cis isomers and high-pressure liquid chromatography analyses ofphotoisomerisation via the triplet state. J Phys Chem 92 2101-2108 Hashimoto H and Koyama Y (1989a) Raman spectra of all-trans /3-carotene in the SI and T1 states produced by direct photoexcitation. Chem Phys Lett 163 251-256 Hashimoto H and Koyama Y (1989b) The C=C stretching Raman lines of/3-carotene isomers in the S state as detected by pump-probe resonance Raman spectroscopy. Chem Phys Lett 154 321-325... 

The above assertion could be tested via ultra fast, time-delay, pump-probe experiments which would measure the energy of the probed resonance as... 

In the realization of a pump-probe resonance ionization experiment, two approaches are common these are depicted in Figure 9.2. Both rely on the resonance of the pump photon hi with a transition from AB to an intermediate energy level of AB. However, the (probe) ionization step can be implemented in two ways. Either hv2 is chosen to be simply way above the ionization threshold IP, to guarantee certain but uncontrolled ionization (left part of the figure), or/ij/2 is tuned into resonance with atransition to a specific (v+, 7+) quantum state of the molecular ion (right part of the figure). 

Infrared spectroscopy can also be used to probe resonance in carboxylic acid derivatives. The dipolar resonance structure weakens the C=0 bond and causes a corresponding decrease in the carbonyl stretching frequency (Table 20-2). The IR data for carboxylic acids reported in Section 19-3 refer to the common dimeric form, in which hydrogen bonding reduces the stretching frequencies of both the 0-H and C=0 bonds to about 3000 and 1700 cm respectively. A special technique—vapor deposition at very low temperature—allows the IR spectra of carboxylic acid monomers to be measured, for direct comparison with the spectra of carboxylic acid derivatives. Monomeric acetic acid displays vc=o at 1780 cm similar to the value for carboxylic anhydrides, higher than that for esters, and lower than that of halides, consistent with the degree of resonance delocalization in carboxylic acids. 

The amplitude control allows the ultrasonic vibrations at the probe tip to be set to any desired level. Although the degree of cavitation required to process the sample can readily be determined by visual observation, the amount of power required cannot be predetermined. A sensing network continuously monitors the output requirements, and automatically adjusts the power to maintain the amplitude at the preselected level. Negligible power is required to keep an ultrasonic probe resonating when operated in air. 

Fokker Bond Tester. An ultrasonic inspection technique commonly used for aircraft structures is based on ultrasonic spectroscopy [2]. Commercially available instruments (bond testers) used for this test operate on the principle of mechanical resonance in a multi-layer structure. A piezoelectric probe shown in Figure 3b, excited by a variable frequency sine signal is placed on the surface of the inspected structure. A frequency spectrum in the range of some tens of kHz to several MHz is acquired by the instrument, see Figure 3a. 

The resonance vector analysis has been used to explore all of the questions raised above on the fate of the polyad numbers in larger molecules, the most thoroughly investigated case so far probably being C2FI2- This molecule has been very extensively probed by absorption as well as stimulated emission pumping and dispersed fluorescence teclmiques [, 53, 70 and 71], the experimental spectra have been analysed in... 

Myers A B and Mathies R A 1987 Resonance Raman intensities A probe of excited-state structure and dynamics Biological Applications of Raman Spectroscopy yo 2, ed T G Spiro (New York Wiley-Interscience) pp 1-58... 

Callegari A, Rebstein J, Muenter J S, Jost R and Rizzo T R 1999 The spectroscopy and intramolecular vibrational energy redistribution dynamics of HOCI in the u(OH) = 6 region, probed by infrared-visible double resonance overtone excitation J. Chem. Phys. 111 123-33... 

Infrared and Raman spectroscopy each probe vibrational motion, but respond to a different manifestation of it. Infrared spectroscopy is sensitive to a change in the dipole moment as a function of the vibrational motion, whereas Raman spectroscopy probes the change in polarizability as the molecule undergoes vibrations. Resonance Raman spectroscopy also couples to excited electronic states, and can yield fiirtlier infomiation regarding the identity of the vibration. Raman and IR spectroscopy are often complementary, both in the type of systems tliat can be studied, as well as the infomiation obtained. 

Time-resolved spectroscopy has become an important field from x-rays to the far-IR. Both IR and Raman spectroscopies have been adapted to time-resolved studies. There have been a large number of studies using time-resolved Raman [39], time-resolved resonance Raman [7] and higher order two-dimensional Raman spectroscopy (which can provide coupling infonuation analogous to two-dimensional NMR studies) [40]. Time-resolved IR has probed neutrals and ions in solution [41, 42], gas phase kmetics [42] and vibrational dynamics of molecules chemisorbed and physisorbed to surfaces [44]- Since vibrational frequencies are very sensitive to the chemical enviromnent, pump-probe studies with IR probe pulses allow stmctiiral changes to... 

As already mentioned, electronically resonant, two-pulse impulsive Raman scattering (RISRS) has recently been perfonned on a number of dyes [124]. The main difference between resonant and nom-esonant ISRS is that the beats occur in the absorption of tlie probe rather than the spectral redistribution of the probe pulse energy [124]. These beats are out of phase with respect to the beats that occur in nonresonant ISRS (cosinelike rather tlian sinelike). RISRS has also been shown to have the phase of oscillation depend on the detuning from electronic resonance and it has been shown to be sensitive to the vibrational dynamics in both the ground and excited electronic states [122. 124]. 

Heinz T F, Himpsel F J, Palange E and Burstein E 1989 Electronic transitions at the CaF2/Si(111) interface probed by resonant three-wave-mixing spectroscopy Phys. Rev. Lett. 63 644-7... 

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