One-dimensional scanning

Scattered patterns from polymers may be photographed using a Polaroid instant camera (Polaroid Land Film Holder 545). The scattered intensity can be quantitatively monitored by means of a two-dimensional Vidicon camera (1254 B, EG G Co.) coupled with a detector controller (Model 1216, EG G Co.). The analogue simal is digitized and analyzed on an DMA 111 (Optical Multichannel Analyzer) system. The scan rate is typically 30 ms for one-dimensional scan and about 0.5 to 1.5 s for two-dimensional mode depending on the number of pixels chosen for grouping. 

The STM images were recorded at constant tutmeling currents applied in the range between 3 and 30 nA. Time-dependent local changes were specially monitored either by calculating the difference between 2 scan windows of the same substrate domain, recorded at different tunes, or by monitoring a selected part of the surface continuously in a one-dimensional scan and recording the scan dependence on time [4]. 

Spots of samples separated on TLC are two-dimensional in their shapes. Several bands of samples can be run in adjacent lanes on a TLC plate, and scanning in one-dimensional axis through the center axis of each lane can provide mass spectrometric information about the compounds separated. However, high performance TLC and many other forms of TLC use two-dimensional development or circular development methods. A full two-dimensional imaging scan is necessary to discern the location of sample spots on the chromatogram, and to determine the degree of spot overlap if any. There have been far fewer reports of two-dimensional TLC/MS than for one-dimensional scanning... 

Figure 2.11. Proton-Proton shift correlations of a-pinene (1) [purity 99 %, CDCls, 5 % v/v, 25 °C, 500 MHz, 8 scans, 256 experiments], (a) HH COSY (b) HH TOCSY (c) selective one-dimensional HH TOCSY, soft pulse irradiation at Sh = 5.20 (signal not shown), compared with the NMR spectrum on top deviations of chemical shifts from those in other experiments (Fig. 2.14, 2.16) arise from solvent effects...

Botz et al. (29) also demonstrated, by scanning electron microscopy, that application of overpressure increases the density of the layer, which could be one reason for the higher separation efficiency. These results showed that Empore silica TLC sheets enable extremely rapid separations (5-20 min) in one-dimensional OPLC, and gave good resolution. Theoretically, for a 3-D OPLC separations development times of 15-60 min would be required. The separation cube of sheets could be especially useful for micropreparative separations (30). 

The centric scan, one-dimensional, DHK SPRITE measurement was used to study the ingress of lithium. This measurement technique was selected due to the low absolute sensitivity of 7Li (27% of [36]), the small amounts that are present and the short signal lifetimes (bulk Tx of 10 ms and T2 of 120 ps). In addition to the robust, quantitative nature of this technique, lithium is a quadrupolar nucleus and interpretation of the image intensity is more complex than spin % nuclei. Once again Eq. (3.4.2) is quantitatively correct for even quadrupolar nuclei due to the fact the longitudinal steady state does not influence the image intensity. 

In this section we establish the equation of the forward scan current potential curve in dimensionless form (equation 1.3), justify the construction of the reverse trace depicted in Figure 1.4, and derive the charge-potential forward and reverse curves, also in dimensionless form. Linear and semi-infinite diffusion is described by means of the one-dimensional first and second Fick s laws applied to the reactant concentrations. This does not imply necessarily that their activity coefficients are unity but merely that they are constant within the diffusion layer. In this case, the activity coefficient is integrated in the diffusion coefficient. The latter is assumed to be the same for A and B (D). 

NOE Measurements. The one-dimensional NOE data were collected at 300 MHz on a Bruker AM-300 NMR spectrometer operating at 300 K. Because the relaxation times for the protons of the hexa-deuterated compound ranged from O.A s to 3.8 s, delays of 20 s. were used between scans. Values for the T s were also measured and found to range from 0.32 s to 1.5 s all values were consistent with a rotational correlation time of 1.1x10 s. 

Fig. 1. Pulse sequences for determining spin-lattice relaxation time constants. Thin bars represent tt/2 pulses and thick bars represent tt pulses, (a) The inversion-recovery sequence, (b) the INEPT-enhanced inversion recovery, (c) a two-dimensional proton-detected INEPT-enhanced sequence and (d) the CREPE sequence. T is the waiting period between individual scans. In (b) and (c), A is set to (1 /4) Jm and A is set to (1 /4) Jm to maximize the intensity of IH heteronuclei and to (1/8) Jm to maximize the intensity of IH2 spins. The phase cycling in (c) is as follows 4>i = 8(j/),8(-j/) 3 = -y,y A = 2(x),2(-x) Acq = X, 2 —x), X, —X, 2(x), —x, —x, 2(x), —x, x, 2 —x),x. The one-dimensional version of the proton-detected experiment can be obtained by omitting the f delay. In sequence (d), the phase 4> is chosen as increments of 27r/16 in a series of 16 experiments.

The rehydrated samples were obtained by exposing dehydrated samples to water vapor at least three days over saturated NH4GI solution at room temperature. A duraction of 0.5 s between scans were allowed for nuclear spin to recover to their equilibrium magnetization. The one—dimensional Na NMR spectra were recorded by using the spin—echo technique. The strength of the radio-frequency field for the two dimensional nutation experiments was 80 kHz and 128 ti values were used (0 250 /is). Each two- dimensional experiment took about 12 hours of spectrometer time. 

FIGURE 10.13 CARS images of the DNA network, (a) TE-CARS image at on-resonant frequency (1337 cm ). (h) TE-CARS image at the off-resonant frequency (1278 cm ). (c) One-dimensional line profiles of the row indicated hy the solid arrows. The scanned area is 1000 nm x 800 nm. The numher of photons counted in 100 ms was recorded for one pixel. The acquisition time was -12 minutes for the image. The average powers of the (0 and tOj beams were 45 pW and 23 pW at the 800 kHz repetition rate. 

See Scanning tunneling spectroscopy Superconductors 332—334 Surface Brillouin zone 92 hexagonal lattice 133 one-dimensional lattice 123, 128 square lattice 129 Surface chemistry 334—338 hydrogen on silicon 336 oxygen on silicon 334 Surface electronic structures 117 Surface energy 96 Surface potential 93 Surface resonance 91 Surface states 91, 98—107 concept 98... 

Ultraviolet radiation, 797 Undeipotential deposition, 1121, 1313 alloy formation during, 1316 causes of, 1315 definition, 1313 displacement potential, 1316 kinetics of, 1316 lead deposition, 1313 one-dimensional phase formation in, 1316 scanning tunneling microscopy used to study, 1313, 1315... 

Figure 4. Three-dimensional representation of the time-resolved data near 8 = 0 as they appear following one interferometric scan. The sampling interval employed was 1.2656 jxm, corresponding to a Nyquist wavenumber of 3950.7 cm 1. Selection of an interferogram at any time delay following the photolysis laser pulse is possible, and is shown here for t = 150/is. Reproduced with permission from Ref. 37.

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