Secondary spectra

The potential ring-opening of cyclopropane radical cations, breaking the weakened bond of type A radical cations (21 +), has been a subject of both interest and controversy. The ESR spectra of cyclopropane radical cation and its methyl-substituted derivatives decayed at temperatures near 100 K. They were replaced by secondary spectra, in which the protons at one cyclopropane center do not interact with the electron spin. This coupling pattern was interpreted as evidence for a ring-opened trimethylene species (22 +) in which one terminal carbon has rotated into an orthogonal orientation [105, 106, 140]. 

Ground + buildings Ground response spectrum and corresponding time histories Floor response spectra (secondary spectra) and corresponding time histories... 

Fig. 1-8. The experiment of Fig. 1-7 as proof of the presence of two components of widely differing wavelength in the secondary spectrum of tin. Calcium showrs only one component. The primary beam (curve 1), being hardest, is least absorbed. Filtering of the primary beam (1.7) is not pronounced enough to cause noticeable curvature here. (See Fig. 1-5.)...

Although the analysis of the secondary spectrum has not progressed to the point where one can make an accurate computation of the ionization potential of the molecule, nevertheless we may conclude that the spectroscopic data considered yield 15.19 volts as the probable value of that constant. It is possible that further investigation will raise this value several tenths of a volt, but it certainly does not seem as though the spectroscopic data would yield a value as high as the average obtained from electron impact experiments. 

The room was made dark and when a hot glass tube had cooled until it was just barely visible, a fragment of iodine was thrown into the tube, which thereupon filled with luminous vapours. To obtain more brilliancy one heats the vapour of iodine in a Bohemian glass tube by means of an enameller s lamp. The contents of the tube look like a red-hot bar of iron. One may also volatilize iodine around a platinum spiral brought to a vivid incandescence the luminous vapour rises like a real flame about the spiral. It is a case of farm without combustion. The light from the iodine gives a continuous spectrum, or rather a confused primary spectrum one perceives traces of characteristic channellings but no lines of the secondary spectrum. 

Positive ray analysis of the products of ionization in hydrogen shows that under proper conditions Hs" " ions are far more numerous than H2 ions. Prompted by this result the writers have been attempting to discover whether or not any part of the secondary spectrum might be attributed to Ha or Ha". Such a possibility has been discussed in connection with some of the attempts to arrange the lines in series but has not, we believe, been subjected to experimental scrutiny. 

Early spectroscopic observations showed the Balmer lines, the secondary spectrum, and some of the stronger lines of mercury. The latter gradually disappeared after liquid air had been kept on the traps continually for over two weeks and they had been too weak to observe for several weeks before the final photographs were taken. Incidentally, it is interesting that the relative concentration of H dropped off considerably at the same time, as might be expected from the cessation of collisions of the second... 

However, photographs were taken which showed qualitatively a strengthening of the Fulcher bands relative to the rest of the secondary spectrum at the higher pressures which favor Finally by taking an exposure of... 

XXXVIa is photolyzed in a benzene or heptane solution to a radical, which is characterized by the doublet spectrum125, 1341 and which arises in heptane on irradiation by 400—480 nm light already at -65 °C 12 . The intensity of the ESR signal increased with rising temperature. The optimum conditions for measurement were achieved at 10 °C. Further increase of temperature led to the decrease of intensity of the primarily formed radical and a new spectrum was recorded. It is not certain if this secondary spectrum belongs to only one radical of if it results from superimposition position of more radicals. The fast decay of radical intermediates occurred at above 50 °C or after the irradiation had been interrupted. The structure and scheme of the formation of primary radical C was proposed by134 14 . 

P) The y-ray spectrum. For purposes of analysis the y-ray spectrum may be divided into partial spectra. The primary " spectrum may be defined as the spectrum of the y-rays emitted by the capturing state the secondary" spectrum that of the second y-ray to be emitted, i.e., the one that follows the emission of the primary y-ray the "tertiary" spectrum, that of the third y-ray and so on. Then if v [e) represents the number of y-rays of energy e emitted per unit energy range per capture in the w-th spectrum, in the absence of appreciable internal conversion,... 

Fourier Transform Infrared X-ray Absorption Near Edge Structure Extended X-ray Absorption Fine Structure Secondary spectrum... 

The spectrum of the secondary emission, that is, the intensity of X-ray radiation as a function of wavelength is established using a crystal analyzer based on Bragg s law. 

Figure Al.7.12. Secondary electron kinetic energy distribution, obtained by measuring the scadered electrons produced by bombardment of Al(lOO) with a 170 eV electron beam. The spectrum shows the elastic peak, loss features due to the excitation of plasmons, a signal due to the emission of Al LMM Auger electrons and the inelastic tail. The exact position of the cutoff at 0 eV depends on die surface work fimction.

Figure Bl.25.6. Energy spectrum of electrons coming off a surface irradiated with a primary electron beam. Electrons have lost energy to vibrations and electronic transitions (loss electrons), to collective excitations of the electron sea (plasmons) and to all kinds of inelastic process (secondary electrons). The element-specific Auger electrons appear as small peaks on an intense background and are more visible in a derivative spectrum.

Figure Bl.26.22. The energy width W of an ultraviolet photoelectron spectrum from a solid may be used to detemiine the work fimction. Changes in work fimction may be obtained from changes in the cut-off of the secondary electron peak (inset) (Attard G and Bames C 1988 Surfaces (Oxford Oxford University Press)).

Chemical data contain information about various characteristics of chemical compounds and a wide spectrum of methods are applied to extract the relevant information from the data sets. Data analysis, however, not only deals with the extraction of primary information from data but also with the generation of secondary... 

NMR The most helpful signals m the H NMR spectrum of alcohols result from the O—H proton and the proton m the H—C—O unit of primary and secondary alcohols... 

These two vibrations are clearly visible at 3270 and 3380 cm in the IR spectrum of butylamine shown in Figure 22 la Secondary amines such as diethylamme shown m Figure 22 7i> exhibit only one peak which is due to N—H stretching at 3280 cm Ter tiary amines of course are transparent m this region because they have no N—H bonds... 

By passing a continuous flow of solvent (admixed with a matrix material) from an LC column to a target area on the end of a probe tip and then bombarding the target with fast atoms or ions, secondary positive or negative ions are ejected from the surface of the liquid. These ions are then extracted into the analyzer of a mass spectrometer for measurement of a mass spectrum. As mixture components emerge from the LC column, their mass spectra are obtained. 

Lasers are used to deliver a focused, high density of monochromatic radiation to a sample target, which is vaporized and ionized. The ions are detected in the usual way by any suitable mass spectrometer to produce a mass spectrum. The yield of ions is often increased by using a secondary ion source or a matrix. 

The volumetric coefficient h a from the combination of Eqs. (14-178) and (14-179) is useful in defining the effect of variable changes but is limited in value because of its dependence on D. The prodiicl of area and coefficient obtained from a given mass of hqiiid is proportional to (1/D ) for small diameters. The prime problem is that droplet-size estimating procedures are often no better than 50 percent. A secondary problem is that there is no that truly characterizes either the motion or transfer process for the whole spectrum of particle sizes present. See Eqs. (14-193) and (14-194). 

Figure 18.17 Two-dimensional NMR spectnim of the C-terminal domain of a cellulase. The peaks along the diagonal correspond to the spectrum shown in Figure 18.16b. The off-diagonal peaks in this NOE spectrum represent interactions between hydrogen atoms that are closer than 5 A to each other in space. From such a spectrum one can obtain information on both the secondary and tertiary structures of the protein. (Courtesy of Per Kraulis, Uppsala.)...

Figure 6 Typical secondary ion mass spectrum obtained from high-purity silicon using an oxygen ion beam. Major ion peaks are identified in the spectrum.

In quadrupole-based SIMS instruments, mass separation is achieved by passing the secondary ions down a path surrounded by four rods excited with various AC and DC voltages. Different sets of AC and DC conditions are used to direct the flight path of the selected secondary ions into the detector. The primary advantage of this kind of spectrometer is the high speed at which they can switch from peak to peak and their ability to perform analysis of dielectric thin films and bulk insulators. The ability of the quadrupole to switch rapidly between mass peaks enables acquisition of depth profiles with more data points per depth, which improves depth resolution. Additionally, most quadrupole-based SIMS instruments are equipped with enhanced vacuum systems, reducing the detrimental contribution of residual atmospheric species to the mass spectrum. 

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