Gated boxcar

Figure 1. Schematic diagram of the experiment. The time delay At is actually controlled by an external circuit that fires the CO and YAG laser sequentially. The fluorescence is focused onto the slit of a monochromator, detected by a photomultiplier tube, and averaged -with a gated boxcar integrator. (Reproduced with permission from Ref. 1. Copyright 1982, The Combustion Institute.)...

Fig. 6.89 Lifetime measurements with a gated boxcar system with successively increasing gate delay time...

Thorn EMI 9235QB) near the phosphor screen to collect all of the ion signal as the probe laser was tuned over the 0(3Pj) Doppler profile at laser wavelengths of 226.23, 226.06 and 225.65 nm for j = 0, 1 and 2, respectively. The output of the photomultiplier was sent to a boxcar averager gated at the appropriate arrival time. The probe laser power was simultaneously measured with a photodiode in order to normalize the 0(3Pj) signal intensity for fluctuations in laser power. 

Figure 9.12 Experimental setup (Nd YAG) Nd YAG laser (1064 nm, 50 Hz, 8 ns), (S) sample, (P) polarizer, (A) analyzer, (WP) waveplate (half or quarter rotated by steppermotor), (VF) visible-light-blocking filter, (PD) photodiode, (PMT) photomultiplier tube, (IRF) infrared filter, (IF) 532 nm interference filter, (PC) PC for data recording and control of the setup, (BC) boxcar/gated integrator, solid (dotted) line represents light at 1064 nm (532 nm).

Fig. 9. The behavior of the occupied trap concentration n, [Eq. (63)] and the free electron concentration n [Eq. (65)] during and after a light pulse of duration tp. For part (a) the parameters are eni = 0.6ms-1, / = 1.2 ms-1, and x"1 = 11.8 ms"1. For part (b) the parameters are e.i = 0.06, 0.6, and 6 ms"1, respectively, for curves (i), (ii), and (iii). The choice of parameters is for illustrative purposes only and may not reflect a realistic situation. The shape of n, is only approximately correct in the dotted portions. Part (c) shows the gating functions for boxcar and lock-in amplifiers, respectively.

Solutions were flowed through a suprasil flat cell (0.1 mm thickness) at rates between 0.1 - S.O mL/min in order to minimize any interference from signals produced by secondary photolysis of products. Time-resolved polarization evolution profiles for the formation and relaxation of the polarized radicals were measured at a constant magnetic field and monitored by both a Hitachi 40 MHz digital oscilloscope and a Stanford Research Systems gated integrator/boxcar averager at 5 ns resolution, and both coupled to a 486 PC desk-top microcomputer for analysis. 

Fig. 24. The RT emission spectra of the core-shell of Eu Y203/Al203 by site-selective excitation at Xexc = (a) 355, (b) 533.55, (c) 525.97, (d) 526.41 nm. The emission was detected using a boxcar integrator that averaged the signal from a cooled PMT with 15 ps gate and 0.3 ms delay from the pump laser pulse (redraw after (Chen, X.Y. et al.,...

Fig. 2. Typical third-harmonic generation measurement. The beams from the laser source (here either a frequency shifted Nd YAG or a HoTmCnYAG laser) are split into a measurement and a reference beam. The polarization rotator and the polarizer serve as variable attenuator and yield the desired polarization of the input beam. The beam is focused on the sample in the vacuum chamber. The water filter removes the fundamental frequency and the attenuation filters limit the third-harmonic signal to the measurement range of the photomultiplier. The signal from the sample is divided by the reference signal and averaged with a boxcar gated integrator...

The second mode is to run the experiment at a fixed magnetic field and sweep the second boxcar gate over time to collect kinetic information. There are two problems with this approach. Eirst, the experiment must be repeated several times with a slow scan rate in order to get satisfactory S/N. To extract the EPR kinetic curve, the experiment is repeated off resonance and the two curves subtracted. Kinetics are more easily obtained using a high-bandwidth transient digitizer instead of a boxcar, and many researchers perform TREPR in this fashion." ° It is important to note here two... 

---