Laser polarised

Figure 1. a) Polarised extinction spectra of samples with Ag nanoparticles original sample and irradiated at 400 nm in the multi-shot regime (100 pulses in single spot), peak pulse intensity was 0.42 TW/cm2 b) TEM image of deformed nanoparticles after irradiation. The laser polarisation is shown as an arrow c) SAXS intensity distribution from the irradiated sample. The light ring in the centre is the shadow of the beam stop. 

Two NR samples (cured and uncured) were studied. In all studies, the samples were stretched to 500% elongation. The Fourier-transform Raman spectrum of NR is presented as a function of time of cold soaking at -25C and of strain with respect to laser polarisation. Under both sets of conditions, changes occur in the spectra that can be attributed to crystallisation. Difference spectra showing only those bands due to crystallisation (i.e. spectra of crystalline NR) are presented, which allows the crystallisation process to be discussed with respect to the conditions under which crystallites are formed. A combination of Fourier-transform Raman and Fourier-transform IR depolarisation spectra was used to deduce preliminary assignments for some of the vibrational bands of natural rubber. 40 refs. 

R.E. Teets, F.V. Kowalski, W.T. HiU, N. Carlson, T.W. Hansch, Laser polarization spectroscopy, in Advances in laser Spectroscopy. SPIE Proc., vol. 113 (1977), p. 80 R. Teets, Laser polarisation spectroscopy. PhD thesis, Physics Department, Stanford University, 1978... 

An apparatus for NMR spectra of laser-polarised Xe on single crystal surfaces has been described."" Single-file diffusion in one-dimensional nanochannels has been explored by laser-polarised Xe NMR spectroscopy." Hyperpolarised Xe-mediated cross-polarisation to material surfaces has been observed at room temperature and above." ... 

A comparison of H and Xe NMR spectroscopy as a probe of the effect of crosslinking in rubbery materials has been published. The size dependency and wall effect of the Ti of laser-polarised Xe gas have been investigated. The measurement of surface-area-to-volume ratios in soft porous material using laser-polarised Xe has been examined and it was proposed that the method is applicable to lungs. ... 

Zhou et al. have sueeessfully transferred the spin polarisation of laser-polarised Xe to the proton spins in the soUd state via spin polarisation-induced nuclear Overhauser effect (SPINOE). " The solid-state NMR signal enhancement factor of 6 for H was observed, eompared with the Boltzmann polarisation signal at 1.879 T and 142 K. This method is likely to be valuable for applications in both NMR spectroscopy and chemical physics. 

Figure 4.14 Comparison of dichroic IR and Raman spectra of drawn PET. Upper IR spectra measured with E parallel and perpendicular to the draw axis. Lower Raman spectra with laser polarised parallel and perpendicular to the draw axis. Note how the 1615 cm and 1018 cm bands have parallel character, while the 875 cm band has perpendicular character with respect to the draw direction (and hence the polymer chain axis).

Figve 7.14 The FT Raman measurements on crosslinked natural rubber stretched and relaxed and recorded in two ways as illustrated. Laser polarised vertically. 

Fig. 8. Principle of the magnetooptical read-out of domain patterns by the polar Kerr effect. The polarisation plane of the incoming laser beam is rotated clock- or counterclockwise according to the orientation (up or down) of the magnetic moments.

In the following sections, we first show the phonon dispersion relation of CNTs, and then the calculated results for the Raman intensity of a CNT are shown as a function of the polarisation direction. We also show the Raman calculation for a finite length of CNT, which is relevant to the intermediate frequency region. The enhancement of the Raman intensity is observed as a function of laser frequency when the laser excitation frequency is close to a frequency of high optical absorption, and this effect is called the resonant Raman effect. The observed Raman spectra of SWCNTs show resonant-Raman effects [5, 8], which will be given in the last section. 

Production of fluorescent LCs by dissolving fluorescent dyes in host materials has been an active area of smdy for many years. This is because it is the simplest method for producing fluorescent LCs and also because the absorption and emission profiles of the dyes can be altered by application of an electric field. Examples of potential applications include polarised organic lasers, but the main problem with the use of fluorescent dyes in guest-host systems is the limited solubility of the... 

Fig. 4.54. Laser-induced steady-state luminescence spectra of alexandrite (a-c) and chrysoberyl (d) demonstrating different Cr and possibly V centers. Vertical polarisation - straight line, horizontal polarization - dash line...

The interaction between the electric dipole of light and the polarisability of molecules or dielectric particles produces a force of the order of piconewtons. By using one or more tightly focussed laser beams, this tiny force can be exploited to move molecules or nanoparticles and arrange them into particular structures. Presently, building up a structure in this way is too slow to be technologically useful. 

Fluorescence depolarisation by energy transfer (rather than rotational relaxation) between donor molecules of the same type can occur. Eisenthal [174] excited solutions of rhodamine 6G (9 mmol dm-3) in glycerol with 530 nm light from a frequency-doubled neodymium laser. The polarisation... 

In the work by Willemsen and co-authors [84] the three Stokes polarization parameters were studied during polarization switches in a vertical-cavity semiconductor laser. It was demonstrated that when the linear part of the absorptive anisotropy is close to zero [127], the laser is bistable and switches stochastically between two polarisations [128]. The analysis of large fluctuations of polarizations in this system [84] reveals what authors have called a stochastic inversion symmetry (see Fig. 10), which is analogous to the time-reversal symmetry observed for the model (17) and shown in Fig. 7. 

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