Picosecond Photon Echo and Coherent Raman Measurements on Molecular Solids in a High Pressure Diamond Anvil Cell

Abstract

We report the first picosecond photon echo measurements on a molecular solid in a high pressure diamond anvil cell at low temperature. We also present time-resolved coherent Raman measurements of vibrational relaxation in pure molecular crystals as a function of pressure in a diamond anvil cell at low temperature. Since photon echo spectroscopy eliminates inhomogeneous dephasing, we utilize this technique to yield the homogeneous dephasing rate for high pressure samples where sample inhomogeneities and inhomogeneous pressure gradients may exist. Since the Fourier transform of the photon echo decay yields the absorption lineshape, these experiments provide a means of obtaining high resolution spectra under extreme high pressure conditions. In addition, pressure induced changes in vibrational relaxation rates observed by picosecond coherent Raman measurements are used as a sensitive probe of the intermolecular interactions that give rise to relaxation phenomena.

Key Words:

• high pressure
• photon echo spectroscopy
• coherent anti-stokes raman spec. (CARS)
• low temperature dynamics
• molecular crystals