Primary pulsed

Table 11.1 shows a comparison of some parameters of small and large seismic events. The size of the source determines the duration of the primary pulse (the slip velocity is independent of the source size) and thus the upper limit of frequency spectra which corresponds to the reciprocal of pulse duration. On the other side with increasing frequency, i.e. with smaller source dimensions, the mean attenuation of elastic waves increases and, therefore, the distance between sensors has to be reduced to smaller values. 

Perform the ME-SIMS experiment in such a way that the analysis is conducted in the static SIMS regime. This can be achieved with a primary ion beam current of 450 pA, a primary pulse length of 30 ns, a spot diameter of 500 nm, and a primary ion energy of 15 kV. At 3 min per experiment this results in a primary ion dose of 4.9 x 10 ions/cm see Note 6). 

This function is periodic, with period T equal to the cavity round-trip time (Fig. 9.16) it corresponds physically to the fact that one light pulse is propagating back and forth inside the cavity at all times. Since part of this pulse is transmitted outside the cavity everytime it strikes the output coupler reflector, the laser output consists of a train of pulses equally spaced in time by T The zeros in E(r) on either side of the primary pulse peaks are separated by the duration 2T/ 2k + 1), which gives an upper bound estimate cf the laser pulse width Tp. For a 1-m optical path length cavity, the round-trip time T is 2Ejc = 6.67 ns. If 9 axial modes are forced to oscillate in phase with equal... 

The source of radiation is a linear accelerator with selectable primary energies of 6, 9 or 11 MeV ( VARIAN Linatron 3000 A). The output of the LINAC at 9 MV is 3000 rad ( 30 Gy) per minute. The pulse length is 3.8 microseconds with repetition frequencies between 50 and 250 Hertz. 

Figure Bl.15.11. Fomiation of electron spin echoes. (A) Magnetization of spin packets i,j, /rand / during a two-pulse experiment (rotating frame representation). (B) The pulse sequence used to produce a stimulated echo. In addition to this echo, which appears at r after the third pulse, all possible pairs of the tluee pulses produce primary echoes. These occur at times 2x, 2(x+T) and (x+2T).

The electron-spm echo envelope modulation (ESEEM) phenomenon [37, 38] is of primary interest in pulsed EPR of solids, where anisotropic hyperfme and nuclear quadnipole interactions persist. The effect can be observed as modulations of the echo intensity in two-pulse and three-pulse experiments in which x or J is varied. In liquids the modulations are averaged to zero by rapid molecular tumbling. The physical origin of ESEEM can be understood in tenns of the four-level spin energy diagram for the S = I = model system... 

With M = He, experimeuts were carried out between 255 K aud 273 K with a few millibar NO2 at total pressures between 300 mbar aud 200 bar. Temperature jumps on the order of 1 K were effected by pulsed irradiation (< 1 pS) with a CO2 laser at 9.2- 9.6pm aud with SiF or perfluorocyclobutaue as primary IR absorbers (< 1 mbar). Under these conditions, the dissociation of N2O4 occurs within the irradiated volume on a time scale of a few hundred microseconds. NO2 aud N2O4 were monitored simultaneously by recording the time-dependent UV absorption signal at 420 run aud 253 run, respectively. The recombination rate constant can be obtained from the effective first-order relaxation time, A derivation analogous to (equation (B2.5.9). equation (B2.5.10). equation (B2.5.11) and equation (B2.5.12)) yield... 

Section 13 18 One of the special techniques for distinguishing carbons according to the number of their attached hydrogens is called DEPT A series of NMR measurements using different pulse sequences gives normal nulled and inverted peaks that allow assignment of primary secondary tertiary and quaternary carbons... 

Precisely controllable rf pulse generation is another essential component of the spectrometer. A short, high power radio frequency pulse, referred to as the B field, is used to simultaneously excite all nuclei at the T,arm or frequencies. The B field should ideally be uniform throughout the sample region and be on the order of 10 ]ls or less for the 90° pulse. The width, in Hertz, of the irradiated spectral window is equal to the reciprocal of the 360° pulse duration. This can be used to determine the limitations of the sweep width (SW) irradiated. For example, with a 90° hard pulse of 5 ]ls, one can observe a 50-kHz window a soft pulse of 50 ms irradiates a 5-Hz window. The primary requirements for rf transmitters are high power, fast switching, sharp pulses, variable power output, and accurate control of the phase. 

The construction of a TXRF system, including X-ray source, energy-dispersive detector and pulse-processing electronics, is similar to that of conventional XRF. The geometrical arrangement must also enable total reflection of a monochromatic primary beam. The totally reflected beam interferes with the incident primary beam. This interference causes the formation of standing waves above the surface of a homogeneous sample, as depicted in Fig. 4.1, or within a multiple-layered sample. Part of the primary beam fades away in an evanescent wave field in the bulk or substrate [4.28],... 

In TOF-SIMS, the source of primary ions is pulsed at a rate of a few kHz. The pulse width is on the order of 1 ns. Secondary ions ejected from the sample surface are accelerated through a potential V and then drift through a field-free TOF analyzer with different velocities, depending on their masses. The drift velocity of an ion with charge-to-mass ratio zjm can be determined from the expression ... 

Pulse-jet cleaning (above) uses a controlled blast of compressed air from the primary into the secondary nozzle, which is magnified by induced air being drawn into the bag. The sudden release of air causes the bag to expand fully, throwing the dust from the outer surface. Dislodged dust falls into the collection hopper. At right, types of duty cycles... 

Below Vi volts. The pulse of electrons reaching the positively charged central wire will contain somewhat less than 400 electrons owing to some decrease of primary ionization through recombination, which occurs because the field is too low. 

To evaluate die patient s response to tiierapy, and depending on die drug administered, die nurse may check die patient s blood pressure every hour, inquire whether pain has been relieved, or monitor die pulse every 15 minutes. After evaluation, certain otiier decisions may need to be made and plans of action implemented. For example, die nurse may need to notify die primary health care provider of a marked change in a patient s pulse and respiratory rate after a drug was administered, or die nurse may need to change die bed linen because sweating occurred after a drug used to lower die patient s elevated temperature was administered. 

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