Cm-1 Line Research Articles

Tin as a Vacancy Trap in Silicon at Room Temperature

Silicon samples which contain a high concentration of dispersed tin have been irradiated at 80°, 140° or 300°K with 3 MeV electrons. The interaction of defects (vacancies and interstitials) with tin was studied by infrared absorption measurements. The tin-vacancy pair was found by monitoring the release of vacancies when the pair anneals near 460°K. Vacancies released from tin are then trapped on oxygen to form the oxygen-vacancy defect which is measured by the strength of the 835 cm-1 line. Because vacancies are trapped at room temperature by tin atoms, tin aids in the separation of vacancy and interstitial associated defects in silicon. An absorption band at 935 cm-1 produced independent of the tin concentration is attributed to silicon interstitials trapped by oxygen in Si. This interstitial defect is stable to 330°K. Applications to devices are suggested.

Interaction of Frenkel excitons with phonons in anthracene

A canonical transformation of the original Hamiltonian of an interacting exciton-phonon system is used to obtain a new exciton-phonon interaction term. From the partly diagonalized Hamiltonian the mean free path of the renormalized exciton is calculated. Numerical results are obtained for the 40000 cm-1 line of anthracene. The polarization has only a small effect on the selfenergy in this case but the mean free path, particularly its temperature dependence, is changed significantly by the renormalization.

Laser-excited Raman spectra of micro sample

The Raman spectrum of minute amount of CCl4 was obtained in an extremely short time, by employing the oscillation line at 4880 Å of argon-ion laser for the excitation. The output of the laser was kept on less than 250 mW throughout the measurement. A light prism spectrograph for convenience of the photographic measurement and a simple optical system around Raman cell characterized the apparatus.Amount of the sample used was 330 μl, and the exposure time was 315 min. with Eastman Kodak 103a-F plate. An overtone of 760 cm-1 line was observed at 1539 cm-1 by elongated exposure. In the case of an extremely small amount of the sample, oscillation lines of the laser other than 4880 Å must be screened by an interference filter.

Symmetry of a colour centre in magnesium oxide

The symmetry of the centre responsible for the 9570 cm-1 (10 450 A) line, which appears in the absorption spectrum of neutron-irradiated magnesium oxide, has been investigated at 77 °K by analysis of the polarization spectra of the line under uniaxial stress. The line is associated with a [110] linear electric dipole oscillator in a centre which has orthorhombic symmetry and [110] orientation. The peaks in the phonon-assisted spectrum of the line can be explained by taking 280 cm-1 and 380 cm-1 as the energies of the fundamental phonon modes. There is some evidence for a second zero-phonon line at 10 070 cm-1 having phonon energies of 380 cm-1 and 490 cm-1.