High pressure flow system for the H2 saturated water. Before the experiment water solution is transferred to the 500 ml vessel V1 for saturation with H2 at high pressure. Then the solution is pressed into the closed loop system using two syringe pumps (P1 and P2). If all two-port valves are closed and the six-port valve (SPV1) is switched to the sample, the solution can be recirculated through the heat exchanger, heater H1, and the sample tube in the EPR cavity at constant pressure by pressing from one syringe pump to another. For the details see text.
Free induction decay (FID) of the H atom high field line at 30 °C measured in quadrature (dots vs. solid line). The signal represents an average of 20 000 pulses.
Measured hfcc (green line) and comparison to the 3D harmonic potential model of Roduner et al. 25 (red dashed line).
Difference of aqueous H atom g-factor measurement and free electron g-factor (g 0) vs. temperature. Red dots and red error bars represent raw data. Green line with blue error bars incorporates the constraint that g-factor shift with temperature is proportional to hfcc shift (see text for the details). Smaller and thicker green error bars show the modified error amplitudes that would apply apart from the field calibration uncertainty.
Resonant frequencies for H atom low field line at 306.0 mT vs. high field line at 358.0 mT for the whole temperature range. Green crosses represent frequencies for both H atom lines with arms equal to the errors at each temperature point. Red line is a linear approximation for the set.
Free induction decay of the H atom low field line at 303 °C measured in quadrature. The signals represent an average over 160 000 pulses. This signal is the worst case S/N ratio used in the present report.
Comparison of the experimental reduced hfcc (circles) with two classical model fits, based on H2 partial molal volume (dashed) and water density (solid line).
Partial molar volume of the H2 molecule (red hole squares) compared to that for water itself (green solid squares) and a calculated mean free path for the molecule (blue solid triangles) at 220 bars pressure. H2 is considered an excellent model for the H atom in water. 10
Hyperfine coupling and g-factor for aqueous H atom determined in various studies.
Values for static compression and collisional distortion terms of the reduced hfcc, optimized near room temperature and at the hfcc minimum temperature.
Article metrics loading...
Full text loading...