Line-narrowing

Dugan M A and Albrecht A C 1991 Radiation-matter oscillations and spectral line narrowing in field-correlated four-wave mixing I theory Rhys. Rev. A 43 3877-921... 

The development of tunable, narrow-bandwidtli dye laser sources in tire early 1970s gave spectroscopists a new tool for selectively exciting small subsets of molecules witliin inhomogeneously broadened ensembles in tire solid state. The teclmique of fluorescence line-narrowing [1, 2 and 3] takes advantage of tire fact tliat relatively rigid chromophoric... 

Lee H W H, Walsh C A and Payer M D 1985 Inhomogeneous broadening of eleotronio transitions of ohromophores in orystals and glasses analysis of hole burning and fluoresoenoe line narrowing experiments J. Chem. Phys. 82 3948-58... 

A monochromator is useful not only for removing unwanted lines from the X-ray source but also for narrowing the otherwise broad lines. For example, each of the MgXa and AlXa doublets is unresolved and about 1 cY wide at half-intensity. A monochromator can reduce this to about 0.2 cY This reduction of the line width is very important because in an XPS specttum, unlike an ultraviolet photoelectron specttum, the resolution is limited by the line width of the ionizing radiation. Unfortunately, even after line narrowing to 0.2 cY... 

At high excitation fluence (2.4 mJ/cm2) the emission spectrum collapses into a narrow line located at 2.53 eV (see Fig. 8-2 a, dashed line), slightly blue-shifted with respect to the low intensity emission. The process strongly depends on the shape of the excitation area. For a rectangular spot, line narrowing occurs at 55 pj/cm2, i.e. 45 times a lower fluence than for a small circular spot, while the... 

In the previous section we have shown that for an excitation density above the PL line-narrowing threshold, the shape of the SE spectrum remain unchanged. This demonstrates that the spontaneous emission spike is not due to a new transition existing in the phoioexcited material, as would be the case for excitonic mol-... 

In this section experimental results are described, which are obtained by applying the conventional pump-probe technique to m-LPPP films kept in vacuum at the temperature of liquid nitrogen [25], These results allow the identification of the primary excitations of m-LPPP and the main relaxation channels. In particular, the low and high excitation density regimes are investigated in order to get an insight into the physical processes associated with the emission line-narrowing phenomenon. 

The width of this Lorentzian line is half as large as that found in (3.37). This, however, is not a surprise because the perturbation theory equation (3.23) predicted exactly this difference in the width of the line narrowed by strong and weak collisions. This is the maximal difference expected within the framework of impact theory when the Keilson-Storer kernel is used and 0 < y < 1. 

In this manner the necessary condition (4.16) of the line narrowing effect is satisfied only for the doublet that belongs to the Q-branch. This result reflects the fact that a rotational phase shift does not affect Q-branch... 

Two line narrowing techniques, matrix isolation and resonant laser excitation, are being used separately and in combination to eliminate inhomogeneous broadening (94). Microenvironmental inhomogeneities are reduced by freezing the sample into uniform site locations in isolation or Shpol skii matrices (95). Alternatively, with highly monochromatic and tunable lasers, it is possible to photoexcite only the subset of emitter sites in a low temperature matrix which have... 

Larsen OFA, IS Kozin, AM Rija, GJ Stroomberg, JA de Knecht, NH Velthorst, C Gooijer (1998) Direct identification of pyrene metabolites in organs of the isopod Porcello scaber by fluorescence line narrowing spectroscopy. A a/ Chem 70 1182-1185. 

G. (1994) Eluorescence-line narrowing in CdSe quantum dots - surface localization of the photogenerated exciton. Phys. Rev. B, 50, 2293-2300. 

FLNS Fluorescence line-narrowing GPC Gel permeation chromatography (see... 

Grzesiek S, Kuboniwa H, Hinck AP, Bax A. Mutiple-quantum line narrowing for measurement of Ha-Hp J couplings in isotopically enriched proteins. J Am Chem Soc 1995 117 5312-5315. 

Figure 4.14 shows the ESR spectrum of [Mn(CO)(dmpe)Cp]+. Clearly, the parallel features are rather variable in line width, with the low-field lines broad and the high-field lines narrow. The ESR parameters for this spectrum49 are given in Table 4.15 where (j is the angle between the g-matrix z-axis and the hyperfine matrix z-axis. 

It has recently been demonstrated that the analysis of MAS sidebands patterns can be used to study molecular dynamics in the solid state [85-88]. Indeed, the line narrowing effect of MAS can be partly offset, or completely eliminated, if the 2H quadrupole tensor is reoriented due to motion on a time scale comparable to (first-order quadrupolar broadening, such motion-induced effects should be less evident in the DQMAS spectrum, as has indeed been observed by Wimperis and colleagues in several deuterated solids [87, 88]. For example, the simulation of the SQ spectrum of tetrathionate dihydrate-cfi yielded the same reorientational rate constant as the previously described quadrupolar echo approach (Fig. 6). 

For rigid Si-F bonds, the 19F CSA is characterized by a span, Q = Sn - S33, of about 80 ppm [150]. This parameter describes the total static linewidth of 19F NMR of rigid Si-F bonds in zeolites. Line narrowing (reduced span values) is observed, when the fluoride ion carries out motional jumps between two or more Si sites. 

Ci-C6 alkanes/interactions among guest molecules H MAS NMR linewidths (effect of molecular motion on MAS line narrowing) [198]... 

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