A sample cell and low-temperature accessory design for fluorescence-mode x-ray absorption spectroscopy of air-sensitive and corrosive compounds

Abstract

A sample cell and low-temperature cooling unit design suitable for x-ray absorption spectroscopy (XAS) of oxygen and/or water sensitive compounds is presented. The cell is a simplified and optimized modification of a previously suggested design. The low-temperature accessory is specifically designed for good thermal isolation and equilibration at liquid nitrogen temperatures, eliminating the need for a more expensive commercial cryostat. The entire construction can be directly attached to an ion chamber and either a standard Lytle detector or energy-discriminating germanium-element solid-state detector via helium gas-purged adaptor flanges. The apparatus was tested at liquid nitrogen temperatures and gave good temperature stability within ±0.1 K. The XAS signal from an air-sensitive potassium/pyrene complex at 100 K taken at the X-6B beam line at the National Synchrotron Light Source facility at Brookhaven National Laboratory is presented.