CO/pH2 - A Molecular Thermometer
Abstract
We utilize reversible temperature dependent changes in the infrared absorption spectrum of CO molecules in solid parahydrogen (pH2) to probe the temperature profiles of the matrices during deposition. The intensity of a well-resolved absorption feature near 2135 cm(-1) shows monotonic increase with temperature over the 2 to 5 K range. The initial state of this transition is estimated to be 7.9(+/-0.5) K above the ground state of CO/pH2. During the deposition of 100 PPM CO/pH2 samples, we detect temperature gradients of appr. 10 K/cm in samples subjected to estimated heat loads of appr. 10 mW/cm2. The resulting estimated thermal conductivities of appr. 1 mW/cm-K (0.1 W/M-K) are four orders of magnitude lower than the conductivity of single crystal solid pH2, and more than an order of magnitude lower than previously measured for pH2 solids doped with 100 PPM concentrations of heavy impurities.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 30, 1998
- Accession Number
- ADA408625
Entities
People
- Mario E. Fajardo
- Simon Tam
Organizations
- Air Force Research Laboratory