Physical width

The gates referred to above can be created in various ways. For example, suppose that the probe beam goes tlirough the sample, but only half of its physical width (in the sample) is crossed with the pump beam. Now, if we have two photodiodes, one can measure the intensify of the perturbed part of the probe beam, whilst the second measures the unperturbed part as a result of creating spatial gates, the two recorded output signals can be used to measure the... 

This parameter arises from the spectral band which is selected by the exit slit and will reach the detector. This is not the physical width of the exit slit which cannot be less than several micrometres. 

This has the consequence that the photodiodes can be made longer, which is of importance for X-ray applications. Cell dimensions of up to 25 pm x 2.5 mm are commercially available in arrays with up to 1024 elements. The spatial resolution is given by the physical width of the individual cells, which in this case is 25 pm. 

The ideal adsorbed solution theory of Myers and Prausnitz [13] has been used for developing a multicomponent isotherm model based on the single component isotherm at any pore size. The following result is obtained for the multicomponent isotherm for each component studied in a pore of physical width H (=/f -0.3354)... 

Atomic spectral lines have a physical width as a result of several broadening mechanisms [12]. 

Furthermore, isotopic structure and hyperfine structure, and also resonance broadening, resulting from the interaction between radiating and non-radiating atoms of the same species, and Stark broadening, resulting from interaction with electrical fields, contribute to the physical widths of the spectral lines. 

Owing to the line broadening mechanisms, the physical widths of spectral lines in most radiation sources used in optical atomic spectrometry are between 1 and 20 pm. This applies both for atomic emission and atomic absorption line profiles. In reality the spectral bandwidth of dispersive spectrometers is much larger than the physical widths of the atomic spectral lines. 

Accordingly, it was very soon found that using sources for which the physical widths of the emitted analyte lines are low is more attractive. This is necessary so as to obtain high absorbances, as can be understood from Fig. 76. Indeed, when the bandwidth of the primary radiation is low with respect to the absorption profile of the line, a higher absorption results from a specific amount of analyte as compared with that for a broad primary signal. Primary radiation where narrow atomic lines are emitted is obtained with low-pressure discharges as realized in hollow cathode lamps or low-pressure rf discharges. Recently, however, the availability of narrow-band and tunable laser sources, such as the diode lasers, has opened up new per-... 

Cu, oo describes the influence of the radiation source, (dfJy/dl) is the spectral radiation density for the background intensity, B0 is the radiant density for an analytical line at the concentration c = 1 and A7L is the physical width of the analysis line. The second term (Ai) describes the influence of the spectral apparatus. 

Fig. 20. (a) Model nitrogen adsorption isotherms at 77 K calculated using a modified Kelvin-BET method for carbon slit pores of physical width (reading from left to right) 10.0,11.4,14.3, 21.4 and 42.9 A [138]. (b) Comparison of pore filling pressure correlations for DFT (points) and the MK-BET method (line) for nitrogen adsorption in carbon slit pores at 77 K [139]. 

As I line at 228.812 nm with the Gd I line at 228.802 nm. In such a case, an alternative line should be used. However, this may also be problematic if the analyte has few sensitive lines, as in the case of cadmium. When a higher resolution spectrometer, such as an echelle spectrometer, is used the lines are farther apart than their physical widths. However, interference is still possible through broadened line wing overlap or stray light. 

The instrumentation required to perform FCCE is relatively simple. The power supply can be any commercially available HVDC power source, but an ideal power supply would have dual polarity, 0-30 kV at several 100 elA, with safety interlocks and computer control capabilities. The maximum voltage needed is determined by the desired electric field strength and length of the capillary. In order to allow for some margin of error in control of the counter flow, the minimum length of capillary should be at least three to four times the physical width of the desired separation window. These margins allow for the analyte bands to be maintained within the inner half of the capillary so that they are not pushed out on either side of the capillary, with detection occurring in the center of the capillary. 

Sf is the spectral slit width corresponding to the physical width of the spectral line (AAf) and Rf = A/AAf, the resolution required to resolve the line width, s is the slit width corresponding to the optical aberrations in the spectral apparatus and is... 

Line Broadening. Atomic spectral lines have a physical width resulting from several broadening mechanisms [10], The natural width of a spectral line results from the finite lifetime of an excited state, T. The corresponding half-width in terms of frequency is ... 

This approach was introduced by Koirthyo-HANN and Pickett in 1965 [159] and is now provided in almost every AAS system. TTie total absorption resulting from the presence of the element and the background absorption are measured with hollow cathode lamp radiation, but, in addition, a continuum source is used which measures only the background absorption. This is possible as the monochromators used in AAS have a large spectral band width compared with the physical width of the resonance line emitted by the hollow cathode source, and the width of the absorption... 

Here H is the physical width of the pore, which is defined as the distance from the plane passing through carbon atoms of the outermost layer of one wall to the corresponding plane of the opposite wall. This formula was suggested by Everett and Fowl [16] and Kaneko et al. [17] for 1-Site model. For the 5-Site models, the accessible volume is calculated based on the pyramid configuration of methane becanse it is energetically favorable. 

The pore size distribution is denoted as f(H), with dV = f(H)dH being the physical volume of pores having physical widths falling in the range between H and H + dH. The corresponding accessible pore volume is dV = (H /H) f(H)dH. Therefore, the specific physical and accessible pore volumes (m /kg) are calculated from... 

First we show the adsorption isotherm of a very small pore (6.5 A). This pore can only accommodate one layer. Figure 4a shows the simulated absolute adsorption isotherm as well as the mass excess density isotherm using the 5-site model. The solid line with black symbols is the absolute density based on the accessible pore width, while the dashed line is that based on the physical width. The solid line is the excess density. 

Figure 4. Isotherms of methane adsorption at 273 K (solid line with symbols is the density based on accessible width dashed line is the density based on physical width solid hne is the excess density) (a) 6.5 A sht pore (b) 10 A slit pore...

Figure 9 Lateral resolution in SPR microscopy. The vertical lines denote the physical width of a 2.5 nm Si02 ridge. Number insets correspond to the various wavelengths used.

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