Raman Spectrum of Diamond

Abstract

The erstand second-order Raman spectra of diamond were studied using the 4880' and 5145 A lines of an Ar ion laser and the 6328A. line of a He-Ne laser. The spectra were recorded at room, liquid-nitrogen, and liquid-helium temperatures. In addition to the second-order spectrum previously reported by Krishnan, a new weaker second-order spectrum was observed in the range 1600 -2100 cm '. Polarization studies were carried out on both the erstand second-order spectra. From such studies it was established that the 1332cm ' Raman line is the zone-center optical phonon with P &"+& (F2,) symmetry. The prominent features in both the second-order Raman spectra reported here and the second-order infrared spectra are interpreted in terms of the critical points of the phonon dispersion curves established from neutron spectroscopy and on the basis of space-group selection rules. '

Comparing phonon dephasing lifetimes in diamond using Transient Coherent Ultrafast Phonon Spectroscopy

“…The observed widths of the literature, however, vary considerably from 1.2 cm − 1 to 4.75 cm − 1 [8,9,12,25,26]. The large variance is due to a number of factors including: spectrometer limitations, source linewidths, isotopic mass defects, nitrogen impurities, cyrstal boundaries, and stress gradients [3].…”

“…(7) and (8). Since the pump pulses are temporally separated, we assume that the second Stokes generation is initialized by B(T + τ) in Eq.…”

“…Traditionally, the phonon lifetime has been indirectly measured via the inverse of the first order Raman linewidth [8]. More recently, time-domain techniques have been developed that directly probe the time evolution of sample reflectivity or transmissivity, following impulsive phonon excitation with few-femtosecond laser pulses [9] and can achieve high relative resolution [10].…”

Terahertz Sum-Frequency Excitation of a Raman-Active Phonon

“…2(f) is a clear hallmark of diamond's F 2g phonon. Its decay is known to result from anharmonic interactions with other lattice modes [28,44].…”

“…We focus on the zone-center F 2g optical phonon at Ω=2π ≈ 40 THz, which is one of the highest phonon frequencies known. This mode has a vanishing electric dipole moment but is strongly Raman active [26][27][28]. The underlying symmetric C-C stretch vibrations [ Fig.…”