Development of a total reflection X-ray fluorescence spectrometer for ultra-trace element analysis

A simple and fairly inexpensive total reflection X -ray fluorescence (TXRF) spectrometer has been designed, constructed and realized. The spectrometer is capable of ultra -trace multielement analysis as well as performs surface characterization of thin films. The TXRF setup comprises of an X-ray generator, a slit - collimator arrangement, a monochromator/ cutoff-stage, a sample reflector stage and an X -ray detection system. The glancing angle of incidence on the two reflectors is implemented using a sine -bar mechanism that enables precise angle adjustments. An energy dispersive detector and a GM counter are employed for measu ring respectively the fluorescence intensities and the direct X -ray beam intensity. A Cu -target X-ray generator with its line focus window is used as an excitation source. The spectrometer is quite portable with its compact design and use of a peltier cooled solid state detector for energy dispersive detection. Alignment and chara cte- rization of the TXRF system has been performed and the minimum detection limits for various elements have been determined to be in the range of 100 pg to 5 ng even at low X-ray generator powers of 30 kV, 5 mA. The capability of the TXRF system developed for thin film characterization is also demonstrated.