H D Analysis Employing Energy Transfer from Metastable ExcitedState He in Double-Pulse LIBS with Low-Pressure He Gas

ABSTRACT: A laser-induced-breakdown-spectroscopy (LIBS) experiment with a unique double-pulse setup and operated in low-pressure (3 kPa) He ambient gas is performed to study the detection of light elements, such as hydrogen (H) and deuterium (D), as well as elements of high excitation energies, such as ?uorine (F) and chlorine (Cl), which are usually di?cult to detect using ordinary LIBS techniques. A nanosecond Nd:YAG laser operated in its fundamental wavelength with energy of 54 mJ is focused onto the Al target to generate the He plasma. Another picosecond Nd:YAG laser operated in its fundamental wavelength with energy of 2 mJ is focused onto the sample surface and activated 2 ?s before the operation of the nanosecond laser. The application to polyvinyl chloride (PVC) and polytetra?uoroethylene (PTFE) samples produces sharp and high-intensity Cl- and F-emission lines. Meanwhile, the sharp and well-resolved H?D-emission lines with merely 0.18 nm wavelength separation are also clearly detected from a zircaloy sample. Further measurement of a set of zircaloy samples containing di?erent concentrations of D yields a linear calibration curve with a zero intercept. The detection limit of D is found to be about 10 ppm.