Pressure scanning

The absorption signal seen varies from a small value at lowest pressures to a peak occurring when spectral line and cavity have comparable widths, before 

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Adamaik B and Mathieu C 2000 The reduction of the beam gas interactions in the variabie pressure scanning eiectron microscope with the use of heiium gas Scanning 21 178... 

Surface Mobility of Atoms and Molecules Studied with High-Pressure Scanning Tunneling Microscopy... 

High pressure processors, 13 411 High pressure scanning electron microscopy (hpsem), 16 466 High pressure solvent exchange kinetics studies, 13 433-435... 

Yeh and Keeler 244) extended the method of laser-scattering spectroscopy to probe systems undergoing rapid chemical reactions. They observed the spectral line broadening in light from a singlemode He-Ne laser scattered from multicomponent solutions, as a function of time. The experiment employed a pressure-scanned Fabry-Perrot interferometer and photon counting techniques. 

A 10% aliquot of the digestion mixture was analyzed on a Vydac C18 250 im ID fu silica cap aiy column connected on-line to ESI-MS (4). A linear gradient of 2% B to %% B in 45 minutes using solvent A (0.1% TFA) and solvent B (90% acetonitrile, 0.07% TFA) was used with a flow rate of 2 jul/min. Sample elution was monitored by UV detection at 200 nm. Mass spectra were recorded in the positive ion mode using a TSQ-700 triple quadrupole instrument (Fiimigan-MAT, San Jose, CA) with an electrospray ion source opo ating at atmospheric pressure. Scans were continuously acquired every three seconds between la/z 500 and 2(XX) in the centroid mode. 

Later, the pressure-scanning technique was used to investigate the thermophysical properties, isobaric molar heat capacity Cp (J K" mol" ), and Up, over extended T and p of several fluids or their mixtures, such as quinoline, n-hexane, 1-hexa-namine, and its binary mixtures with 1-hexanol, m-cresol, and its binary mixtures with quinoline, etc. As a rule, for simple liquids without strong intermolecular interactions, such as -hexane, for example, both the C -isotherms and the pressure effects (isotherms) on the isobaric heat capacity at pressures up to 700 MPa exhibit minima. It is worth recalling that the pressure effect on the Cp is related to the iso-baiic thermal expansibility ttp by the following equation (the effect of pressure on the Up is discussed in the next section) ... 

Hendriksen BLM, Bobaru SC, Frenken JWM (2004) Surf. Sci. 552 229 Hendrik-sen BLM (2003) Model Catalysts in Action High-Pressure Scanning Tuimehng Microscopy. Ph.D. Thesis, Universiteit Leiden... 

In permeate return mode, permeate was recombined with retentate and recirculated. This mode was used to observe the effect on flux of increasing filter pressure (a pressure scan) or increasing transfilter flow (a flow scan). 

A pressure scan was made by holding transfilter flow constant and making a series of trials at differing filter pressures. In similar manner, a flow scan was made by holding filter pressure constant and making a series of trials at different transfilter flows. All pressure and flow scans were 60 min in duration, sufficient to establish flux change. 

A nondestructive method may be applied to a sample with relatively simple composition, but for a more complex sample, digestion processes are recommended, which are destructive. Beam analysis is recommended as a nondestructive method for samples with simple composition. The reliability of the analytical information for the beam analysis technique is assured by reproducibility and homogeneity of surfaces. It is necessary to clean the surfaces before the analytical process. Also, there are mechanical steps used for sample preparation to assure surface homogeneity. Conventional scanning election microscopy (SEM) is widely used as an analytical tool.38 4(1 Variable pressure scanning electron microscopy (VP-SEM) opens new opportunities in the field of materials science. Samples such as liquids can be analyzed using the VP-SEM technique without any prior preparation method (e.g., the characterization of two-phase crude petroleum from the... 

Figure 23. Detail of the phase diagram of Nj on graphite near the tricritical point obtained from vapor pressure scans at fixed temperature. (Adapted from Fig. 1 of Ref. 237.)...

Figure 6.17b Pressure scans of formaldehyde at 145603 MHz diluted with air. Paraldehyde was maintained at elevated temperature under a flow of air at 100 mLmin that was sampled into the spectrometer...

Figure 6.17d Pressure scan of acrylonitrile at the 8js-7]7 154724MHz transition in nitrogen passed over the liquid at 2(fC...

The samples were examined by variable pressure scanning electron microscopy (SEM) with a LEO 1450 VP microscope (Zeiss, Oberkochen, Germany). 

Tetramethyl polycarbonate CO2 195 6.6 5.62 160 [120] High pressure scanning calorimetry... 

Fig. 4.46. Photoelectric recording of a Doppler-broadened laser-excited fluorescence line of Na2 molecules in a vapor cell and the Doppler-free scattered laser line. The pressure scan Ap = a corresponds to one free spectral range of the FPI...

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