TEM analyses of basalt alteration experiments under Venus-relevant conditions

Experimental alteration products were characterized using the Johnson Space Center JEM-2500SE scanning transmission electron microscope (STEM), which provided elemental analyses of the samples at high spatial resolution (i.e., on the nanometer scale). Qualitative data, using energy dispersive x-ray spectroscopy (EDS) elemental mapping (via x-ray counts produced from each element), were collected to identify chemically altered regions of the samples by depicting—on the micron scale—the distribution of cations. Thereafter, nanometer scale traverses in EDS were used to quantitatively analyze the elemental chemistry of the selected region; quantification was achieved by the Cliff-Lorimer method (Cliff and Lorimer, 1975), comparing the intensities of characteristic elemental x-ray emissions with those of standard materials.