title: Controlling residual hydrogen gas in mass spectra during pulsed laser atom probe tomography.
abstract: Residual hydrogen (H2) gas in the analysis chamber of an atom probe instrument limits the ability to measure H concentration in metals and alloys. Measuring H concentration would permit quantification of important physical phenomena, such as hydrogen embrittlement, corrosion, hydrogen trapping, and grain boundary segregation. Increased insight into the behavior of residual H2gas on the specimen tip surface in atom probe instruments could help reduce these limitations. The influence of user-selected experimental parameters on the field adsorption and desorption of residual H2gas on nominally pure copper (Cu) was studied during ultraviolet pulsed laser atom probe tomography. The results indicate that the total residual hydrogen concentration,HTOT, in the mass spectra exhibits a generally decreasing trend with increasing laser pulse energy and increasing laser pulse frequency. Second-order interaction effects are also important. The pulse energy has the greatest influence on the quantityHTOT, which is consistently less than 0.1 at.% at a value of 80 pJ.
authors.affiliation: Department of Materials Science and Engineering, University of Maryland, 2144 Chemical and Nuclear Engineering Bldg., #090, College Park, MD 20742-2115 USA.
authors.forename: R Prakash
authors.identifier: 0000-0003-1345-1735
authors.initials: RP
authors.lastname: Kolli
keywords: Atom probe tomography (APT); Copper; Hydrogen; Laser pulsing