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Notes: The magnetization (M) in IV–VI based diluted magnetic semiconductors is expressed as a sum of contributions due to isolated impurities, pair interactions, lattice diamagnetism, and spin density due to carriers. We calculate the contribution of each of these mechanisms for p-type Pb1−xMnxTe for different x and magnetic field (H) and compare the results with experiment.

Notes: Local spin-density theory and the linear combination of Gaussian orbitals method are employed to compute the band structure and ferromagnetic moment of nonequilibrium phases of several transition metals. The calculations are used to investigate possible magnetic order in these nonequilibrium phases, which include bcc and fcc Mn in a wide range of lattice constant, and bcc Nb and fcc Rh in regions of expanded lattice constant. The ferromagnetic moment calculations reveal transitions from nonmagnetic to ferromagnetic states and/or transitions from low-spin to high-spin ferromagnetic states as the lattice constant increases. In the case of bcc Mn, fcc Mn, and bcc Nb, large ferromagnetic moments are found in the expanded lattice constant region.

Notes: The time-resolved Tn←T1 resonance Raman spectra of quinoline (1-azanaphthalene), isoquinoline (2-azanaphthalene), quinoxaline (1,4-diazanaphthalene), and quinazoline (1,3-diazanaphthalene) molecules in cyclohexane solution are reported, and vibrational assignments and structural implications are discussed. In each of the four compounds, the most resonance enhanced Raman band lies in the 1340–1270 cm−1 region and corresponds to nuclear displacements involving in-plane stretching motions of the CC and CN bonds. In diazanaphthalenes, drop in the frequency of this vibration on S0 to T1 excitation (97 cm−1 in quinoxaline, 76 cm−1 in quinazoline) is observed to be higher than in azanaphthalenes (31 cm−1 in quinoline, 58 cm−1 in isoquinoline) implying pronounced elongation of the CN bonds, in comparison to the CC bonds, in the T1 states. The T1 Raman spectra of azanaphthalenes, in contrast to naphthalene, are observed to exhibit significant solvent dependency.

Notes: We report, in this paper, submicrosecond time resolved resonance Raman spectra of anilino radical and its radical cation as observed in pulse radiolytic studies of the oxidation of aniline in aqueous solution. By excitation in resonance with the broad and weak electronic transition of anilino radical at 400 nm (ε∼1250 M−1 cm−1) we have observed, for the first time, the vibrational features of this radical. The Wilson ν8a ring stretching mode at 1560 cm−1 is most strongly resonance enhanced. The ν7a CN stretching band at 1505 cm−1, which is shifted to higher frequency by 231 cm−1 with respect to aniline, is also prominent. The frequency of this latter mode indicates that the CN bond in the radical has considerable double bond character. The Raman spectrum of aniline radical cation, excited in resonance with the ∼425 nm electronic absorption (ε∼4000 M−1 cm−1), shows features which are similar to phenoxyl radical. Most of the observed frequencies of this radical in solution are in good agreement with vibrational energies determined by recent laser photoelectron spectroscopic studies in the vapor phase. The bands most strongly enhanced in the resonance Raman spectrum are, however, weak in the photoelectron spectrum. While the vibrational frequencies observed for anilino radical and its isoelectronic cation are quite similar, the resonance enhancement patterns are very different. In particular the ν14 b2 mode of anilino radical observed at 1324 cm−1 is highly resonance enhanced because of strong vibronic coupling between the 400 nm 2A2–2B1 and the higher 2B1–2B1 electronic transitions.

Notes: Resonance Raman spectra of the photoexcited lowest triplet (3B+2u) state of naphthalene (N-h8 and N-d8), observed in solution by time-resolved technique, are reported. Eight Raman bands (396, 496, 741, 958, 1337, 1395, 1440, and 2676 cm−1) have been observed in N-h8 and ten (479, 690, 754, 1005, 1142, 1281, 1356, 2491, 2638, and 2714 cm−1) in N-d8. Vibrational assignments are briefly discussed.

Notes: The vibrational and electronic structures of p-phenylenediamine radical cation have been studied using time-resolved resonance Raman spectroscopy and molecular orbital calculations. The Raman spectra in aqueous solution show striking variations in intensity profile when excitation is varied from 340 to 480 nm. Excitation in resonance with the 460–480 nm absorption shows enhancement of only totally symmetric vibrations. Most prominent are the δNH2 scissor mode at 1658 cm−1 and the Wilson modes ν8a (CC stretch) at 1644 cm−1, ν7a (CN stretch) at 1423 cm−1, and ν9a (CH bend) at 1184 cm−1. Also observed are ν1 (ring breathe) at 840 cm−1 and ν6a (CCC bend) at 467 cm−1. With excitation in the 340–410 nm region the ν1 band becomes relatively stronger and an additional band at 1524 cm−1 appears. This latter band, which dominates the spectrum at 360 nm, is assigned to the nontotally symmetric vibration ν8b (CC stretch) having b3g symmetry that gains intensity through vibronic coupling. Raman spectra of ring- and amine-deuterated radicals allow distinction of overtone and combination bands enhanced by Fermi resonance from fundamentals due to δNH2 and ν8a (CC stretch) modes in the 1600–1700 cm−1 region. The theoretical calculations show reasonable agreement with the observed vibrational frequencies and lead to detailed information on the bond structure and normal modes of the radical. The calculated CN bond lengths of 1.33 A(ring) are intermediate between lengths typical of single and double bonds in aromatic amines. The calculations also allow interpretation of the experimental absorption spectrum. The broad medium intensity absorption peaked at 460 nm with a shoulder at 480 nm is assigned to a 2B3u ←2B2g transition, the very weak 360 nm absorption to 2Au ← 2B2g and the very strong ∼325 nm absorption to a higher 2B3u ← 2B2g.Calculations with the simple relation Ik∝ (V'k)2/ωk, which requires evaluation only of vertical excited state gradients, are found to satisfactorily describe the dramatic changes in Raman intensity profile that are observed with different excitation wavelengths. The 460 and 480 nm Raman spectra are governed by scattering from the lowest 2B3u state. Spectra taken in the 410–340 nm range are governed mainly by preresonance scattering from the higher 2B3u state, which is vibronically coupled to the weak 2Au state via the b3g symmetry ν8b (CC stretch) vibration. The relative intensities of totally symmetric modes calculated for excitation into the two 2B3u excited states agree well with those in the two distinct patterns observed experimentally.