Probe spectroscopy

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. 

Section 13 20 IR spectroscopy probes molecular structure by examining transitions between vibrational energy levels using electromagnetic radiation m the 625-4000 cm range The presence or absence of a peak at a charac tenstic frequency tells us whether a certain functional group is present Table 13 4 lists IR absorption frequencies for common structural units... 

We discuss the rotational dynamics of water molecules in terms of the time correlation functions, Ciit) = (P [cos 0 (it)]) (/ = 1, 2), where Pi is the /th Legendre polynomial, cos 0 (it) = U (0) U (it), u [, Is a unit vector along the water dipole (HOH bisector), and U2 is a unit vector along an OH bond. Infrared spectroscopy probes Ci(it), and deuterium NMR probes According to the Debye model (Brownian rotational motion), both... 

Okabayashi N, Paulsson M, Ueba H, Konda Y, Komeda T (2010) Site selective inelastic electron tunneling spectroscopy probed by isotope labeling. Nano Lett 10 2950-2955... 

Salamon, Z. Brown, M. I. Tollin, G., Plasmon resonance spectroscopy Probing molecular interactions within membranes, TIBS 1999, 24, 213 219... 

J.R. Lakowicz, Topics in Fluorescence Spectroscopy Probe Design and Ghemical Sensing, Plenum, New York, 1994. 

In contrast to STM current-voltage — Vt) spectroscopy, which was discussed in Section 4.1, where the feedback loop has to be open during operation and where the energy dependence of the LDOS is obtained, STM z — Vt spectroscopy probes the DOS via the voltage-dependent tip displacement z at constant f. Figure 4.27(a) shows an idealized z — Vt spectrum of a thin him, which typically consists of three regions, indicated by A, B and C. 

Figure 8 shows the attenuation length of electrons in solids as a function of their kinetic energy. The few theoretical calculations available cire in good agreement with these empirical data Only unscattered electrons convey useful information, while scattered electrons contribute to a structureless background (secondary electrons). From Fig. 8, it is clear that photoelectron spectroscopy probes at most a few tens of Angstroms. 

In this work we investigate such interactions by fluorescence spectroscopy. Probe molecules such as 2-naphthol and its 5-cyano-derivative are effective chromophores for studying acid/base interactions since both are relatively strong photo-acids. In addition, 2-naphthol is a common solute for which SCF solubility and physical property data exist. Ultimately, spectroscopic information will be used to develop a clearer picture of the specific interactions which induce large cosolvent effects on solubility in SCF solutions. 

Szmacinski H, Lakowicz JR (1990) Topics in fluorescence spectroscopy. Probe design and chemical sensing, vol 4. Plenum, New York... 

Additional work by the Forster group, making use of transient emission spectroscopy, probed the rate of photoinduced electron transfer between metal centers within a novel trimeric complex [Os(II)(bpy)2(bpe)2 ] [Os(II) (bpy)2Cl]2 4+, where bpy is 2,2/-bipyridyl and bpe is fra s-l,2-bis-(4-pyridyl) ethylene. Transient emission experiments on the trimer, and on [Os(bpy)2(bpe)2]2+ in which the [Os(bpy)2Cl]+ quenching moieties are absent, reveal that the rate of photoinduced electron transfer (PET) across the bpe bridge is 1.3 0.1 x 108s-1. The electron transfer is believed to be from the peripheral Os(II)Cl metal centers to the [Os(bpy)2(bpe)2]2+ chro-mophore. Comparison to rate constants for reduction of monolayers at a Pt electrode reveals that the photoinduced process is significantly faster [39]. 

In bioinorganic chemistry, spectroscopy probes the geometric and electronic structure of a metallobiomolecule active site allowing the correlation of structure with function (Figure l.l).7... 

Vibrational Spectroscopy [Infrared (mid-IR, NIR), Raman]. In contrast to X-ray powder diffraction, which probes the orderly arrangement of molecules in the crystal lattice, vibration spectroscopy probes differences in the influence of the solid state on the molecular spectroscopy. As a result, there is often a severe overlap of the majority of the spectra for different forms of the pharmaceutical. Sometimes complete resolution of the vibrational modes of a particular functional group suffices to differentiate the solid-state form and allows direct quantification. In other instances, particularly with near-infrared (NIR) spectroscopy, the overlap of spectral features results in the need to rely on more sophisticated approaches for quantification. Of the spectroscopic methods which have been shown to be useful for quantitative analysis, vibrational (mid-IR absorption, Raman scattering, and NIR) spectroscopy is perhaps the most amenable to routine, on-line, off-line, and quality-control quantitation. 

We turn now to a more detailed description of the photoionization probe step in order to clarify the ideas presented above. Time-resolved photoelectron spectroscopy probes the excited-state dynamics using a time-delayed probe laser pulse that brings about ionization of the excited-state wave packet, usually with a single photon... 

Spectromicroscopy — Most optical spectroscopies probe rather large areas or volumes because the beam of light (whether infrared, UV-Vis, or X-ray etc.) probing the electrochemical interface or the electrolyte solution volume in front of the electrode (the interphase) has a finite diameter ranging from several 10 micrometers to a few millimeters or even more. Thus, spatially or locally resolved information cannot be obtained. Employing confocal or near-field optics very small surface areas can be probed, resolutions down to a few micrometers are possible. 

Peisach, J.. (1995) ESEEM spectroscopy - probing active site structures of metalloproteins, Bioradicals Detected by ESR Spectroscopy 203-215. 

The gaseous reaction of 4 did not occur below 65 °C. Above that temperature, reactivity was indicated by colour changes of the crystalline material from red-purple to white. The reaction could also be monitored by IR spectroscopy, probing the v(N-N) absorption at 2125 cm-1, which was replaced by two v(Co-H) absorptions at 1967 and 1833 cm-1. Treatment of the dihydrogen complexes with N2 afforded the starting material 4. 

The temperature distribution is not only a function of radius, but also depends on the stellar luminosity, the disk geometry, and may depend on the accretion rate (see Table 8.1 and Section 3.3) for example, at a given radius irradiated flared disks will be warmer than flat disks. Naturally, hotter stars will heat their disks to higher temperatures at a given radius thus, mid-infrared spectroscopy probes different radii in different disks. 

Nuclear magnetic resonance (NMR) spectroscopy probes the energy required to flip a nuclear spin in the presence of a magnetic field. Computation of this effect... 

NMR spectroscopy probes transitions between nuclear spin states. The transition frequencies and relaxation times contain a wealth of information related to molecular structure and dynamics. Transition frequencies also reveal couplings between nuclear spins, and between electron and nuclear spins. The primary experimental observables in NMR are the chemical shift, which is related to the transition frequency, and the line width, which is related to the relaxation time. In paramagnetic systems, both of these parameters have the potential to be affected significantly by the unpaired electron, requiring special interpretation of data but also revealing information on the nature of the metal site. To make full use of NMR to study complex systems such as metallobiomolecules, it is important to understand the factors that influence observables in NMR. 

Single-Molecule Photon-Stamping Spectroscopy Probing spFRET and Nanosecond Anisotropy... 

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