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The temperature dependence from ambient to 2325 K of the high frequency E2g mode intrinsic to the hexagonal phase of boron nitride has been determined using a pulsed-excitation gated-detection technique which effectively discriminates against sample blackbody emission. A monotonic decrease of 80 cm−1 in mode frequency accompanied by a marked increase in linewidth was observed over this temperature range. Simultaneous acquisition of both Stokes and anti-Stokes Raman scattering has been demonstrated and provides another method by which sample temperatures may be verified. Variations in measured linewidth and mode frequency are described in terms of an anharmonic oscillator model from which the intralamellar thermal expansion coefficient is estimated.

Raman spectra of the hexagonal phase of boron nitride to temperatures exceeding 2000 °C. have been recorded using a pulsed -excitation gated -detection method. Surface temperatures were determined during rapid sample heating from analysis of corrected Stokes /anti-Stokes intensity ratios and from shifts in the resonance frequency of the 1366 cm-1 E9 mode. Successive spectra were acquired at time intervals as short as 33 msec corresponding to the pulse repetition frequency of the probe laser. Using this synchronous detection technique, the time evolution of graphite furnace temperatures was determined from measured spectra. Results indicate nearly complete rejection of sample blackbody radiation from the Raman scattered light at these high temperatures. A nearly linear relationship between the Eg resonance frequency and temperature was found. Phonon linewidths were also found to increase by a factor of three over this temperature range.

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