Frequency shift in

First, it is possible to excite a chromophore corresponding to the active site, and detennine which modes interact with it. Second, by using UV excitation, the amino acids with phenyl rings (tryptophan and tyrosine, and a small contribution from phenylalanine) can be selectively excited [4], The frequency shifts in the resonance Raman spectrum associated with them provide infomiation on their enviromnent. 

GiessibI F J 1997 Forces and frequency shifts in atomic-resolution dynamic-force microscopy Phys. Rev. B 56 16 010... 

Laser Doppler Velocimeters. Laser Doppler flow meters have been developed to measure Hquid or gas velocities in both open and closed conduits. Velocity is measured by detecting the frequency shift in the light scattered by natural or added contaminant particles in the flow. Operation is conceptually analogous to the Doppler ultrasonic meters. Laser Doppler meters can be appHed to very low flows and have the advantage of sensing at a distance, without mechanical contact or interaction. The technique has greatest appHcation in open-flow studies such as the deterrnination of engine exhaust velocities and ship wake characteristics. 

In the second technique, the flowing liquid must contain scatters in the form of particles or bubbles that will reflect the sound waves. These scatters should be travehng at the velocity of the hquid. A Doppler method is applied by transmitting sound waves along the flow path and measuring the frequency shift in the returned signal from the scatters in the process fluid. This frequency shift is proportional to liquid velocity. 

The main equation, which allows understanding the physical sense of 0-0 frequency shifts in the spectra after inserting a molecule from gas phase into the solvent, is ... 

In a microwave cavity containing an ionized gas, the resonant frequency shifts in proportion to the electron density n (Slater, 1946). This effect has been used by Warman and Sauer (1970, 1975) to measure n as a function of time... 

Figures 6 and 7 also point out the two principal techniques we have employed in monitoring these oxygen exchange reactions, namely, frequency shifts in the...

The ab initio SCF cluster wavefunction has been used to investigate the bonding of CO and CN- on Cu,0 (5,4,1), (5 surface layer, 4 second layer and 1 bottom layer atoms), and to calculate their field dependent vibrational frequency shifts in fields up to 5.2 x 107 V/cm(46). A schematic view of the Cu10 (5,4,l)CO cluster is shown in Figure 8. In order to assess the significance of Lambert s proposal, that the linear Stark effect is the dominant factor in the field dependent frequency shift, the effect of the field was calculated by three methods. One is by a fully variational approach (i.e., the adsorbate is allowed to relax under the influence of the applied field) in which the Hamiltonian for the cluster in a uniform electric field, F, is given by... 

As with any other homonuclear decoupling, the transverse magnetization of the 13C , for example in the evolution time, is perturbed by the decoupling pulse, resulting in an additional precession virtually around the z axis. Since the adiabatic decoupling is applied during the entire evolution time of the 13C , a non-linear frequency shift rather than a phase shift appears in the spectrum. This is termed the Bloch-Siegert (frequency) shift in the NMR literature in honour of their discovery of the phenomenon. 

Electronic effects Changes in the absorption frequency for a particular group take place when the substituents in the neighbourhood are changed. The frequency shifts, in these cases may be due to inductive, mesomeric or due to field effects and there will be combined effect due to all. The effect of one can only be estimated approximately. 

Mossbauer spectroscopy involves the measurement of minute frequency shifts in the resonant gamma-ray absorption cross-section of a target nucleus (most commonly Fe occasionally Sn, Au, and a few others) embedded in a solid material. Because Mossbauer spectroscopy directly probes the chemical properties of the target nucleus, it is ideally suited to studies of complex materials and Fe-poor solid solutions. Mossbauer studies are commonly used to infer properties like oxidation states and coordination number at the site occupied by the target atom (Flawthome 1988). Mossbauer-based fractionation models are based on an extension of Equations (4) and (5) (Bigeleisen and Mayer 1947), which relate a to either sums of squares of vibrational frequencies or a sum of force constants. In the Polyakov (1997)... 

For the Fe-S proteins, the frequencies and sulfur Isotope dependence of the Fe-S vibrational inodes can be used to distinguish mononuclear, blnuclear, and tetranuclear clusters. Hydrogen bonding of both Fe-0 and Fe-S clusters can be detected by frequency shifts in deuterium-substituted proteins. 

Most of the bonding energies in Table 6.11 have been determined by IR spectra on the basis of the frequency shifts in the the v(OH) or v(NH) regions... 

The Sagnac effect caused by the rotating platform is therefore due to a rotation in the internal gauge space ((1),(2),(3)), which results in the frequency shift in Eq. (171). The frequency shift is experimentally the same to an observer on and off the platform and is independent of the shape of the area Ar. The holonomy difference (172) derived theoretically depends only on the magnitudes and ff, and these scalars are frame-invariant, as observed experimentally. There is no shape specified for the area Ar in the theory, and only its scalar magnitude enters into Eq. (172), again in agreement with experiment. 

Wool, R. P. Measurements of Infrared Frequency Shifts in Stressed Polymers, preprint... 

Figure 2. IR frequency shifts in the silanol stretching vibration region. ( ) poly(styrene-co-4-vinylphenyldiinethylsilanol) (ST-VPDMS), ( ) poly(slyrene-co-4-vinylphenylinethylphenylsilanol) (ST-VPMPS) and (A) poly(styrene-co-4-vinylphenyldisilanol) (ST-VPDPS).

Figure 11. IR absorbance spectra of isotope-labeled PAN CH3C(0)0014N02 and CH3C(0)0015N02 in the frequency region of 500-2000 cm. Values in parentheses in (C) are approximate frequency shifts in cm-1 for 15N-labeled PAN. Band assignments taken from Ref. 95.

In mixtures water and solvents with lone pair electrons, the structure depends on the base strength of the lone pair electrons in the series given on page 9. For example the spectra of water-dioxan (Fig. 14) show a weaker frequency shift in comparison with water-alcohol mixtures (Fig. 12) — that means weaker H-bonds — of the H-bond band of water (1.92 q instead 1.94 /a). The wavelength 1.896 ju in Fig. 14 of the non H-bonded OH band instead 1.89 ju in water/methanol (Fig. 12) corresponds with a non H-bonded water OH group whose second OH is H-bonded (Compare the free OH band in liquid water 200 °C < T< 350° in Fig. 1249 ). 

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