Continuous wave solutions

C60 has been used to produce solvent-cast and LB films with interesting photoelec-trochemical behavior. A study of solvent-cast films of C60 on Pt rotating disc electrodes (RDEs) under various illumination conditions was reported [284]. Iodide was used as the solution-phase rednctant. The open-circuit potential shifted by 74 mV per decade of illumination intensity from a continuous wave (cw) argon-ion laser. The photocurrent versus power was measured at -0.26 V under chopped illumination (14-Hz frequency, vs. SCE) up to 30 mW cm and was close to linear. The photoexcitation spectrum (photocurrent versus wavelength) was measured at 0.02 V (vs. SCE) from 400 to 800 mn and found to be... 

In a continuous wave (CW) magnetic resonance experiment, the radiation field B is continuous and BQ is changed only slowly compared with the relaxation rates (so-called slow passage conditions). Thus a steady-state solution to eqns... 

For the pressure studies, two phase" compact ion behavior is observed with an inflection point between 7 and 11 atms. For the aqueous solution studies, the hydraulic permeability K and the g-ratio are hardly effected by solute type (within experimental error). The solute diffusive permeability however, varies with solute type in good qualitative agreement with free energy parameters, infrared overtone shifts, and spin echo and continuous wave nuclear magnetic resonance spectroscopy results from the literature. 

Muchall et al. (98CC238) have recently investigated the gas-phase thermolysis of 2,5-dihydro-2,2-dimethoxy-2,5,5-trimethyl-l//-l,2,4-oxadiazole (75) by PE spectroscopy. Decomposition of 75 was induced by means of a continuous wave (CW) C02 laser as directed heat source at 26 W, which corresponds to a temperature of 500 50°C. When the PE spectra of acetone, tetramethoxyethene, and dimethyl oxalate were subtracted from the pyrolysis spectrum, a sim-ple spectrum remained that could be identified as that of dimethoxycarbene. Thermolysis in solution (94JA1161) had shown formation of tetramethoxyethene, and FVP experiments (92JA8751) gave dimethyl oxalate, both of which arise from the common precursor, dimethoxycarbene. Thermolysis of oxadiazolines similar to 75 in solution affords dialkoxycarbenes via an intermediate carbonyl ylide (94JOC5071). 

Electron spin relaxation in aqueous solutions of Gd3+ chelates is too rapid to be observed at room temperature by the usual pulsed EPR methods, and must be studied by continuous wave (cw) techniques. Two EPR approaches have been used to study relaxation studies of the line shape of the cw EPR resonance of Gd3+ compounds in aqueous solution, and more direct measurement of Tle making use of Longitudinally Detected EPR (LODEPR) [70]. Currently, LODESR is available only at X-band, and the frequency dependence of relaxation is studied by following the frequency dependence of the cw EPR line shape, and especially of the peak-to-peak line width of the first derivative spectrum (ABpp). 

Again the discrete-time simulation of the decaying traveling-wave solution is an exact implementation of the continuous-time solution at the sampling positions and... 

Phosphorescence of a solid solution of GAV in benzene or in acetonitrile at 77 K was readily observable with a at 530 nm in a cw (continuous wave)... 

Continuous wave instruments involve a considerable waste of time. A solution to the inefficiency of single - frequency observation is to excite all of the nuclei in a sample simultaneously and to observe the total response of the sample. This is done by periodical, intense, short RF pulses. A RF pulse excites a finite band width of frequencies. The detector observes a pattern called a free induction decay (FID). An example is presented in figure C.2. Fourier Transforming this FID, yields the classical NMR spectrum. 

The earliest studies of Mg NMR were largely exploratory and used continuous-wave NMR technology [36-40]. In general, these studies suffered from a lack of instrumental sensitivity. Nevertheless, these exploratory studies demonstrated the ability of Mg NMR to provide information on the chemistry of complexation. One of the first applications of Fourier transform techniques to Mg-NMR was on aqueous Mg" electrolytes (e.g., MgBr2 and MgCU) [41]. Fourier transform NMR made it possible to study concentrations as low as 0.002 M in natural abundance Mg solutions in less than 12 h. 

Fundamental questions related to the electronic configuration of the open or colored forms and the number and structures of the photomerocyanine isomers are considered on the basis of the results of continuous-wave (stationary) and time-resolved (picosecond, nanosecond, and millisecond) Raman experiments. For spironaphthoxazine photochromic compounds, the Raman spectra may be attributed to the TTC (trans-trans-cis) isomer having a dominant quinoidal electronic configuration. Surface-enhanced resonance Raman spectroscopy (SERRS) is demonstrated as a new analytical method for the study of the photodegradation process in solution for nitro-BIPS derivatives. The development of this method could lead to the identification of the photoproducts in thin polymer films or sol-gel matrices and ultimately to control of degradation. 

The proton NMR spectmm shown in Fig. 4.3 has been recorded with a Varian continuous wave instrument at 60 MHz on a dcuterized chloroform solution of PBO. 

In the outer region the wave field is a superposition of the incident wave (1) and the scattered wave. The latter is described by special cylindrical functions (Hankel functions). The cylindrical functions of another type (Bessel functions) also describe the wave motion in the inner region. The conditions at the boundary line between two-dimensional phases allow us to sew together the solutions of the hydrodynamic equations in the inner and outer regions. The wave motion in the transitional region can be rather complicated. However, if we are not interested in the details of the liquid dynamics in the transitional region, we can continue the solutions, which were obtained at a distance from this region, up to the boundary line. 

Although in principle the simple scheme presented in Fig. 5.59 should provide TOCSY spectra, its suitability for practical use is limited by the effective bandwidth of the continuous-wave spin-lock. Spins which are off-resonance from the applied low-power pulse experience a reduced rf field causing the Hartmann-Hahn match to breakdown and transfer to cease. This is analogous to the poor performance of an off-resonance 180° pulse (Section 3.2.1). The solution to these problems is to replace the continuous-wave spin-lock with an extended sequence of composite 180 pulses which extend the effective bandwidth without excessive power requirements. Composite pulses themselves are described in Chapter 9 alongside the common mixing schemes employed in TOCSY, so shall not be discussed here. Suffice it to say at this point that these composite pulses act as more efficient broadband 180 pulses within the general scheme of Fig. 5.60. 

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