Pulse contribution

NjO pulses, contributed to formation/regeneration of Rhodium-containing sites having activity for dissociation of each incoming NjO pulse to Nj plus Oj at 623 K. Possibilities for such formation/regeneration of active sites include the diffusion/desorption of blocking species away from Rhodium-containing sites, which are further considered below in respect of (NiOj) " and Oj. 

As we have seen in Section 3.1 the range foldover phenomenon — clutter returns that correspond to previous radar pulses — contributes to the SBR clutter. Another important phenomenon that affects the... 

The reason two-photon excitation efficiency depends on the spectral phase of the laser pulse is beyond the scope of the peak intensity argument given above. It requires a more detailed consideration of how the pulse contributes to the nonlinear optical transitions. Let us consider, e.g., the case of two-photon excitation at wavelengths corresponding to = 400 nm. In addition to a pair of 800-nm photons, there are multiple combinations of spectral components within the bandwidth of an ultrashort pulse that can combine to cause excitation equivalent to 400 nm. Their wavelengths satisfy the relation particular, one can have photons at... 

When the anthropogenic tritium was noticed, hopes arose that the specific tritium pulses, contributed by the individual tests, would provide a way to accurately date groundwater. However, it turned out that the input values in precipitation varied considerably from one location to another and from one season and year to the next. In addition, complicated mixing takes place in each aquifer, and the mode and extent of mixing of each year s recharge... 

CCF dependences on the -factor of loaded probe vibrators are shown in Fig.4. For s(l) pulses growth of 2 factor increase CCF maximum amplitude and selectivity. In this case the higher the Q, the longer the pulse duration and the more its periods contribute to the processing. F or q(t) pulses rising of g-factor decrease CCF maximum amplitudes and reduce the selectivity. As q(l) pulse consists of a few first periods only its maximum amplitude depends on Q. the higher the Q, the lower the final pulse amplitude, and therefore, CCF amplitude and selectivity. 

Figure Al.6,8 shows the experimental results of Scherer et al of excitation of I2 using pairs of phase locked pulses. By the use of heterodyne detection, those authors were able to measure just the mterference contribution to the total excited-state fluorescence (i.e. the difference in excited-state population from the two units of population which would be prepared if there were no interference). The basic qualitative dependence on time delay and phase is the same as that predicted by the hannonic model significant interference is observed only at multiples of the excited-state vibrational frequency, and the relative phase of the two pulses detennines whether that interference is constructive or destructive.

Figure Al.6.8. Wavepacket interferometry. The interference contribution to the exeited-state fluoreseenee of I2 as a fiinotion of the time delay between a pair of ultrashort pulses. The interferenee eontribution is isolated by heterodyne deteetion. Note that the stnieture in the interferogram oeeurs only at multiples of 300 fs, the exeited-state vibrational period of f. it is only at these times that the wavepaeket promoted by the first pulse is baek in the Franek-Condon region. For a phase shift of 0 between the pulses the returning wavepaeket and the newly promoted wavepaeket are in phase, leading to eonstnietive interferenee (upper traee), while for a phase shift of n the two wavepaekets are out of phase, and interfere destnietively (lower traee). Reprinted from Seherer N F et 0/1991 J. Chem. Phys. 95 1487.

The main cost of this enlianced time resolution compared to fluorescence upconversion, however, is the aforementioned problem of time ordering of the photons that arrive from the pump and probe pulses. Wlien the probe pulse either precedes or trails the arrival of the pump pulse by a time interval that is significantly longer than the pulse duration, the action of the probe and pump pulses on the populations resident in the various resonant states is nnambiguous. When the pump and probe pulses temporally overlap in tlie sample, however, all possible time orderings of field-molecule interactions contribute to the response and complicate the interpretation. Double-sided Feymuan diagrams, which provide a pictorial view of the density matrix s time evolution under the action of the laser pulses, can be used to detenuine the various contributions to the sample response [125]. 

B2.5.351 after multiphoton excitation via the CF stretching vibration at 1070 cm. More than 17 photons are needed to break the C-I bond, a typical value in IR laser chemistry. Contributions from direct absorption (i) are insignificant, so that the process almost exclusively follows the quasi-resonant mechanism (iii), which can be treated by generalized first-order kinetics. As an example, figure B2.5.15 illustrates the fonnation of I atoms (upper trace) during excitation with the pulse sequence of a mode-coupled CO2 laser (lower trace). In addition to the mtensity, /, the fluence, F, of radiation is a very important parameter in IR laser chemistry (and more generally in nuiltiphoton excitation) ... 

Bensasson R V, Land E J and Truscott T G 1993 Excited States and Free Radicals in Biology and Medicine Contributions from Flash Photoiysis and Pulse Radioiysis (Oxford Oxford University Press)... 

A computer-controlled bandpass filter system controls the size of the acquired spectral window. Typically, this is set to about 120% of the desired sweep width. Only frequencies within these limits are allowed to reach the ADC. Those frequencies outside the limits would only contribute to the noise in the final spectmm. The need for this system is dictated by the nonselective nature of the excitation rf pulse. 

Fabric filters are limited by physical size and bag-life considerations. Some sacrifices in efficiency might be tolerated if higher air-cloth ratios could be achieved without reducing bag life (improved pulse-jet systems). Improvements in fabric filtration may also be possible by enhancing electrostatic effects that may contribute to rapid formation of a filter cake after cleaning. 

Cells used for high-temperature measurements in furnaces often consist of silica sample tubes, supported by thin vanadium sleeves. The key to the analysis is whether it is possible to have a container that scatters in a sufficiently predictable way, so that its background contribution can be subtracted. With the current neutron flux available from both pulsed and reactor sources, sample volumes of... 

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