David Hilton, Ph.D.

scripps institution of oceanography

Mass Spectrometry

Mass spectrometers are analytical instruments that can measure isotope ratios. A new rare gas mass spectrometer (MAP215E) was installed in January 2000. It interfaces the laser probe (see below) via a fully-automated preparation line. The mass spectrometer is equipped with an electrostatic analyser (ESA) located immediately behind the collector slit. This device filters out stray ions resulting in extremely low background counts on the multiplier. Clearly, this is a major feature when attempting to measure small ion beams.

A new inlet line has been constructed to interface the laser extraction system (via the bakeable laser sample chamber) to the mass spectrometer. Key features of the system include: (1) fully bakeable all-metal construction; (2) completely automated valve control; (3) turbo- or ion pumping throughout; (4) provision for aliquoting of a (small) fraction of the total gas load for CO2/H2O determination via an on-line capacitance manometer and quadrupole mass spectrometer.