Lines positions donors

When the line positions come from two sources, the spacing is measured from the same source. The 3p i — 2po spacing is included because it allows comparisons with donor centres where the 2p i line is split, as in the oxygen thermal donor spectra t Resonant phonon broadening of 2po, a [118], b [21]... 

Table 6.21. Ionization energies (meV (cm-1 in parentheses)) of the (S,H) EM donor complexes in silicon with the above-defined notations (after [211]). No line positions...

The unknown constituent in the STDs whose spectra are observed in N-containing CZ silicon is denoted X in this figure. The measured shifts depend on the STD considered and on the accuracy with which a peak position can be measured. The FWHMs of most of the STD lines are between 1 and 2cm 1 (0.124 and 0.25 meV) and it is reasonable to assume an uncertainty of one tenth of the FWHM. A complete list of the STD(X), STD(AZ) and STD(H) line positions is given in Ammerlaan s contribution on STDs in silicon [7]. When considering the positions of the lines of the STD(X)-Ar spectra as references, the lines of the STD(A/)-Ar spectra are found to be red-shifted. The values of the most significant A/-induced shifts of the 2p i lines with respect to the positions in Table 6.29 are (in cm-1) for STD-A —1.4, STD-B — 1.5, STD-C —0.5, STD-G —0.9, and this seems to imply that an AZ atom is present in the core of these donor centres. The values of the shifts (positive) of the STD(H) spectra are smaller or non-existent. The largest ones are +0.5... 

Absorption experiments have been performed with qmi silicon B-doped samples. They show a small increase of the line positions with the Si isotope mass, already observed for the P donor lines, which is due to the increase of Eg with the Si isotope mass. For line 1 (lTs-), the estimated shift between qmi 28Si and 30Si is +0.26 cm-1 (+33peV), and it reaches +0.38 cm-1 (+47 peV) for line 13 (31V ). The corresponding IS for /V0(l>), is about +0.41 cm-1 or +51 peV [161]. These measurements also show that while no sharpening with respect to the FWHMs in natural silicon is observed for some lines like 1, 5, 7, and 8, the FWHMs of other lines can be reduced by an order of magnitude in qmi silicon. With this reduction of the FWHM, a splitting due to the presence... 

The most important results are given in Figure 4-1. The oxygen atom lies 244 pm from the N(l) atom of the diazonio group, well within the sum of the van der Waals radii. The diazonio group deviates by 10.4° from linearity. It seems that the 0(1) N(l) interaction is attractive, as indicated by the angle of 169.6° (instead of 180°) at N(l), but the 0(1) N(2) interaction is not. The NN distance (109.9 pm) is, however, not different from normal values found in diazonium ions. The same authors demonstrated later (Wallis et al., 1993) that this result is not unique for the quino-line-8-diazonium-l-oxide salt, as it was found also for two 1-naphthalenediazonium tetrafluoroborates substituted in the 8-position with the electron donors -SCH3 and -N(CH3)2 and - perhaps unexpectedly - for 8-nitronaphthalene-l-diazo-... 

Figure 7 shows the positions of FL absorption and fluorescence spectra (in centimeter-1) as a function of %. As it is seen, the graphs for different neutral solvents show linear dependence, whereas for protic solvents (alcohols), a different line can be drawn. Such graphs can be practically used for the determination of n in different samples and solvents. If the measured value will be placed on the line for alcohols, this means that the site of our probe incorporation possesses proton donor property. 

There are a number of heteroatoms that can substitute for either boron or carbon in the carboranes. The groups that are as electron-deficient as BH groups are listed vertically to the left of the center line in Table V, whereas those that are as capable as carbon in donating electrons are listed to the right of the center line. The transition elements for the most part electronically substitute for boron and occupy high-coordination sites, but upon electron demand the transition element may also substitute for carbon and concomitantly occupy low-coordination sites. Several transition element moieties, by contrast, are one more electron deficient than boron and occupy, as would be anticipated, high-coordination positions and require additional electron donors (CH groups) to counter the electronic deficit (XIII-24). 

Dialysis units provided highly efficient means for increasing selectivity in a dynamic system by placement in front of a lithium-selective electrode constructed by incorporating 14-crown-4 ether 3-dodecyl-3 -methyl-1,5,8,12-tetraoxacyclotetradecane into a PVC membrane that was in turn positioned in a microconduit circuit by deposition on platinum, silver or copper wires. The circuit was used to analyse undiluted blood serum samples by flow injection analysis with the aid of an on-line coupled dialysis membrane. For this purpose, a volume of 200 pL of sample was injected into a de-ionized water carrier (donor) stream and a 7 mM tetraborate buffer of pH 9.2 was... 

Scheme 4.2 Bond energy as a function of hydrogen position (black solid line), assuming identical pff, values for the donor and acceptor, relative to the lowest vibrational energy level of the hydrogen atom (highlighted by a dotted line), (a) A standard, symmetric hydrogen bond (b) the corresponding low-barrier hydrogen bond (LBHB). The red line represents the probability density function [27, 28].

The substituent effects calculated for A show that aromatic and vinylic jT-donors in the para-position have a stabilizing effect on the nitrenium ions that is much larger than is seen in Op. For example, Op for Me, MeO, and Ph are —0.31, —0.78, and —0.18, respectively, while A for 75y (Ar = 4-tolyl), 75cc (Ar = 4-MeOphenyl) and 75n (Ar = 4-biphenylyl) are 8,1 kcal/mol, 22.7 kcal/mol, and 19.3 kcal/mol, respectively. The calculations and experimental data show that a para-phenyl substituent is about as stabilizing for a nitrenium ion as is a para-methoxy substituent. This unusual stabilization is the major reason that correlations of logS vs. cr are so scattered for nitrenium ions. Substituent effects at N are relatively small. Replacement of NH by NAc destabilizes the ion toward hydration by 4.5 l.Okcal/mol. Based on the correlation line, at 20°C this amounts to a predicted increase in by a factor of 4 to 11 when NH is replaced by NAc. The experimentally observed range of 1.5 to 9.0 (Table 1) is very close to this prediction. These calculated substituent effects on the thermodynamics of hydration and the calculated geometries of nitrenium ions (discussed in another section) indicate that for most nitrenium ions the canonical structure II of Scheme 38 is dominant. ... 

Figure 6.48 (a) Effect of doping on the electrical conductivity (solid line) and thermopower (broken line) of polyacetylene. (Following Etemad et al, 1982.) (b) solitons in trans-polyacetylene (i) neutral, (ii) positive and (iii) negative solitons. Arrow marks the boundary between the two symmetric configurations. A, acceptor D, donor. (Following Subramanyam Naik, 1985.)... 

We first note that an isolated atom with an odd number of electrons will necessarily have a magnetic moment. In this book we discuss mainly moments on impurity centres (donors) in semiconductors, which carry one electron, and also the d-shells of transitional-metal ions in compounds, which often carry several In the latter case coupling by Hund s rule will line up all the spins parallel to one another, unless prevented from doing so by crystal-field splitting. Hund s-rule coupling arises because, if a pair of electrons in different orbital states have an antisymmetrical orbital wave function, this wave function vanishes where r12=0 and so the positive contribution to the energy from the term e2/r12 is less than for the symmetrical state. The antisymmetrical orbital state implies a symmetrical spin state, and thus parallel spins and a spin triplet. The two-electron orbital functions of electrons in states with one-electron wave functions a(x) and b(x) are, to first order,... 

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