Background Signals in Quartz

It has been well documented that damage to quartz, either by grinding, polishing or spot heating will cause increased ESR background signal. This is notably due to Si-O and Si-H bond breakage and the formation of unpaired electrons that once occupied these orbitals. A second less well known cause is the exposure to x-rays, gamma radiation, and intense UV radiation. It has been found that Quartz sample tubes, upon storage next to high energy radiation sources, have after a prolonged period exhibited strong EPR centers that were significant enough to cause interference of sample data. Should you have EPR sample tubes that are producing higher than average background signals, we recommend that you ship the tubes to Norell Inc. for re-annealing. The annealing temperatures that we use to prepare quartz sample tubes for EPR are high enough to reform any chemical bonds broken by the above conditions. Please contact our Technical Service Department at 609-909-3700 for further details.