Figure 1.
The experimental setup used for stopped flow SEOP.
A. Shuttling to high-field detection. The hp mixture is transferred to the detection cell by pressure equalization after the noble gas mixtures are hyperpolarized in the SEOP cell for a time period of td by the stopped flow SEOP method. B. Outline of the optical elements used in Fig. 1A. The elements λ/2 plate and second beam splitter were used to control the laser irradiation (B4) to the SEOP cell (i.e. adjustment of the B4/B3 ratio - for details of power dependent measurements see section 2.2).
Table 1.
83Kr and 129Xe literature rate constants used in Eq. 2.
Figure 2.
83Kr spin polarization, P, as a function of SEOP pressure.
83Kr spin polarization as a function of SEOP cell pressure and combined number density ([Kr]+[N2]) at 433 K for four different gas mixtures. See the legend in the figure for symbol explanation. Polarization data are detailed in Table 2. Data analysis using Eq. 8 with and
as fitting parameters is shown in solid lines and resulting values are reported in Table 4. Fitting of the data was also not attempted for values much lower than
; the dotted lines are extrapolations to pressure ranges outside the fitting region.
Table 2.
Maximum noble gas polarization , maximum apparent noble gas polarization
, and corresponding gas pressures extracted from data of Figs. 2 and 3.
Figure 3.
129Xe spin polarization, P, as a function of SEOP pressure.
129Xe spin polarization as a function of the SEOP cell pressure and combined number density ([Xe]+[N2]) at 373 K for four different gas mixtures. Please refer to the legend in the figure for symbol explanation. Polarization data are detailed in Table 2. A. Solid lines represent data analysis with Eq. 8. Extrapolation of these theoretical curves to pressure ranges outside the fitted region are shown by dotted lines. B. Same experimental data as in (A) but the solid lines represent now the data analysis using Eq. 8 with the pressure dependence of the Rb D1 absorption taken into account through Eq. 9. Extrapolation to pressure ranges outside the fitted region are shown by dotted lines. Fitting parameters for (A) and (B) are reported in Table 5A and 5B, respectively.
Table 3.
83Kr and 129Xe values for obtained from fitting of inversion recovery build up data (see Fig. 4) with Eq. S1.A.
Figure 4.
Inversion recovery 83Kr and 129Xe SEOP.
A. Inversion recovery of 83Kr polarization after SEOP time, tp, for two krypton-nitrogen gas mixtures at different SEOP pressures. Please refer to the legend in the figure for symbol explanation. B. Inversion recovery of 129Xe polarization after SEOP time, tp, for two xenon-nitrogen gas mixtures at different SEOP pressures. The inversion recovery data from both (A) and (B) were analyzed using Eq. S1. Polarization data were normalized to their values at for 83Kr and
for 129Xe to visually compare the rate differences of the mixtures and pressures. The obtained rate constants from fitting of both (A) and (B) are reported in Table 3.
Table 4.
Values for and
from fitting experimental data of 83Kr spin polarization as a function of SEOP cell pressure in Fig. 2 using Eq. 8.A.
Table 5.
Values for
, and
rates obtained from the fitting of experimental data of 129Xe spin polarization as a function of SEOP cell pressure (Fig. 3) using Eq. 8.A.
Figure 5.
Rubidium IR absorption linewidth as a function of gas pressure.
A. IR absorption spectrum of Rb in the SEOP cell containing pure krypton gas at 433 K at three different pressures as detailed in the figure legend. The absorption lines experience a pressure broadening and, to a lesser extent, a shift to higher wavelengths with increasing pressure. B. Rb D1 absorption linewidth as a function of SEOP cell pressure at 433 K for pure krypton (solid red triangles), for pure N2 at 433 K (solid green squares), for pure xenon at 373 K (solid black circles), and for a mixture of 50% xenon with 50% N2 (open black circles). The pressure dependence of the absorption linewidth can be approximately described by (dashed lines). Eq. 9 was concluded from the observed linewidth dependence. The linewidth of the narrowed laser and the broadband laser are 0.25 nm and 2.0 nm respectively, and are indicated in the figure by horizontal dotted lines.
Figure 6.
129Xe polarization, P, dependence on laser power.
129Xe spin polarization as a function of SEOP cell pressure for two different gas mixtures at four different SEOP laser power levels. Please refer to the figure legend for symbol explanation. The laser power was measured in the front of the SEOP cell. Data were analyzed using Eq. 8 (utilizing Eq. 9) within the fitting region (solid lines). Extrapolations to pressure ranges outside the fitted region are shown by dotted lines. The fitting procedure is discussed in section 4.9 and the results of the data analysis are listed in Table 6.
Table 6.
Values of rates from fitting of the 129Xe spin polarization data for different laser powers and laser linewidths in Figs. 6 and 7 using Eq. 8.A.
Figure 7.
129Xe polarization, P, dependence on laser linewidth.
129Xe spin polarization as a function of SEOP cell pressure with the line narrowed (0.25 nm linewidth, 17.3 W) and FAP laser irradiation (2 nm linewidth, 15.6 W). Data were analyzed using Eqs. 8 and 9 for fitting region indicated by the solid lines as discussed in section 4.9. Extrapolation using the obtained values of the fitting coefficients to pressure ranges outside the fitting range are shown by dotted lines. Results of this data analysis are listed in Table 6.