Data collection system, laser

A 100-W immersion heater (such as VWR Scientific Inc. 33897-140 a 200-W to 300-W tea/coffee immersion heater can also be used), controlled by a Variac magnetic stirrer and stir bar 1000-mL beaker thermometer with a resolution of 0.02 K (platinum resistance thermometer or calibrated thermistor such as Vernier model TMP-BTA) 1- to 5-mW He-Ne laser (633 nm) or a red (545 mn) or green (532 nm) laser — a battery-operated laser pointer is suitable, but a module with a separate 3-volt power supply, available from Z-Bolt and other sources, will give better power stability for long rans two Polaroid sheets in rotation holders photodetector such as photomultiplier tube or Thorlabs model 201/579-7227 silicon photodiode analog-to-digital data collection system such as Vernier LabPro. 

The overall schematic of the zero creep/laser interferometer system is shown in Figure 2. The system consists of the reactor in which the sample and reference mirrors are located, the interferometer, and the data collection system. The... 

The first data on polymer systems were collected via (laser-) light-scattering techniques [1] and turbidity measurements, further developed by Derham et al. [2,3]. Techniques based on the glass-transition of the polymer-blend constituents were also tested, such as DSC, Dynamic Mechanical Spectroscopy, and Dielectric relaxation [4]. Films made from solutions of... 

EOS models were derived for polymer blends that gave the first evidence of the severe pressure - dependence of the phase behaviour of such blends [41,42], First, experimental data under pressure were presented for the mixture of poly(ethyl acetate) and polyfvinylidene fluoride) [9], and later for in several other systems [27,43,44,45], However, the direction of the shift in cloud-point temperature with pressure proved to be system-dependent. In addition, the phase behaviour of mixtures containing random copolymers strongly depends on the exact chemical composition of both copolymers. In the production of reactor blends or copolymers a small variation of the reactor feed or process variables, such as temperature and pressure, may lead to demixing of the copolymer solution (or the blend) in the reactor. Fig. 9.7-1 shows some data collected in a laser-light-scattering autoclave on the blend PMMA/SAN [46],... 

The prism at the outlet of the laser serves to separate the laser emission of the gas fluorescence and allows for a clean excitation of the sample. For excitation using solid-state lasers, this element is dispensable. The lens (element 5) collects the fluorescent signal and focuses on the aperture of the monochromator. The filter is used to eliminate excitation that is spread over the surface of the sample. The optical chopper serves to modulate the light at a defined frequency, which serves as reference for the lock-in amplifier. A data acquisition system controls the pace of the monochromator and reads the signal of the lock-in, generating the sample s emission spectrum. 

The statistical nature of the turbulent flame required the analysis of many temperature and density data points from separate pulses for accurate results. Thus, an overall computer system was used to control the various components of the combustion probe apparatus, and to collect and interpret the resultant data in an accurate and timely fashion. This system produced a block of data for each laser shot that included information about the Raman signals, LV readings, and ancillary data such as an identifying shot number and corresponding dye laser pulse energy. Typical current operation permits about twenty experimental run conditions daily, with up to several hundred shots per run. 

There has been a considerable decline in the number of papers which deal with the details of techniques of measurement of fluorescence decay. This is no doubt due to the fact that the alternative methods are now essentially well established. Nevertheless a microcomputerized ultrahigh speed transient digitizer and luminescence lifeline instrument has been described . A very useful multiplexed array fluorometer allows simultaneous fluorescence decay at different emission wavelength using single photon timing array detection . Data collection rates could approach that for a repetitive laser pulse system and the technique could be usefully applied to HPLC or microscopy. The power of this equipment has been exemplified by studies on aminotetraphenylporphyrins at emission wavelengths up to 680 nm. The use and performance of the delta function convolution method for the estimation of fluorescence decay parameters has been... 

The direct characterization of an eT mechanism requires a much more complicated technique time-resolved spectroscopy. The solution containing the system under investigation is irradiated by a laser pulse, and the absorption spectra of the solution are consecutively recorded at chosen and very short time intervals (e.g. every 10 ns). If, in the envisaged two-component system F1 M, an M-to-Fl eT process takes place upon illumination, one should be able to measure the absorption spectra of Fl and M" ", as well as their decay, which allows the determination of the lifetime of the transient species F1 M. It goes without saying that very sophisticated and expensive instrumentation is required to carry out this type of experiment. Moreover, the smaller the fluorophore lifetime and the faster the back-electron transfer process, the more rapid and expensive the data acquisition equipment required. In particular, narrow laser pulses and especially fast data collections are needed for systems such as 1, where a short-living polyaromatic fluorophore (anthracene, r = 5 ns) is linked to the electron donor (or acceptor) group by a rather short carbon chain. 

Besides the basic interest in atomic quantities, the values of transition probabilities are used in different fields of research and technology astrophysics, atmospheric physics, plasma physics, thermonuclear-fusion research and development of laser systems. The evaluation of atomic concentrations can frequently be performed from observed light intensities, when direct concentration measurements are not possible. A large data compilation has been performed at NIST [10-13]. Presently, a great part of the data collection and systematization is performed for astrophysical needs within the international Opacity Project and the Iron Project [14,15]. Since 1990, when the Goddard High-Resolution Spectrograph on the Hubble Space Telescope started to work, the demand for transition probabilities for VUV spectral lines dramatically increased [16,17]. 

Figure 2-4. A schematic diagram of die relative timing systems between laser, x-ray and sample photo-conversion hfetime. The nature of steady-state, pseudo-steady-state (in its simplest form) and stroboscopic pump-probe mediods are illustrated. The absolute timing for each method is on a separate scale die entire experiment is shown for die steady-state mediods the pseudo-steady-state representation shows up to the beginnings of die first data-collection frame the stroboscopic representation illustrates a regular pattern that occurs diroughout the experiment. Stroboscopic pseudo-steady-state methods are not represented here per se, but they essentially represent a combination of the basic pseudo-steady-state and stroboscopic methods shown here...

The deflection is measured by using a laser triangulation and parallax method. The laser sensors are responsible for measuring the distance to the pavement surface, and the deflection is calculated from the difference between the slope of the beam and the slope of the pavement at the initial point and after the device moves to the next point. The device is provided with a data acquisition system used for data collection, storage and analysis (Elseifi et al. 2012). 

The main parts of a MALDI-TOF apparatus are the sample holder, including a matrix, optic equipment with a laser, a detector and an analyser. A computer is connected to the apparatus to supervise the electronics of the instrument. Data collected from the detector are transferred to the computer unit. In practice, a solution of the polymer sample in a volatile solvent is adsorbed on the matrix. The deposition is performed using a spotting system, which allows the deposition of sample volume ranging from a couple of nanolitres to a few microlitres. The sensitivity of the detector is extremely high. 

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