Thermal Correction to the Molar Polarizability of a Boltzmann Gas (Brief Report)
Ulrich D. Jentschura, M. Puchalski, Peter Mohr
The metrology of fundamental quantities in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very accurate frequency measurements, the molar polarizability of atomic gases has recently been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Unites (SI) for which an accurate value of the Boltzmann constant is needed. Here, we calculate the dominant shift of the molar polarizability in an an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when the probing electric field is Lorenz transformed into the rest frame of the atoms that undergo thermal motion. While this effect is small when compared to currently available experimental accuracy, the relativistic correction to the dipole interaction is much larger than the thermal shift of the polarizability induced by blackbody radiation.
Physical Review A
Boltzmann constant, polarizability, gas thermometry