Observation of dynamic nuclear polarization echoes

Sci. Adv. 10, eadr2420 (2024) · DOI: 10.1126/sciadv.adr2420 · arXiv: 2406.18246

License: CC BY 4.0.

Abstract

It is demonstrated that the time evolution of the electron-nuclear polarization transfer process during pulsed dynamic nuclear polarization (DNP) can be reversed on a microsecond timescale, leading to the observation of DNP echoes. The DNP echoes are induced by consecutive application of two pulse trains that produce effective Hamiltonians that differ only in the sign of the effective hyperfine coupling. The experiments have been performed on a frozen solution of trityl radicals in water/glycerol on a homebuilt X-band electron paramagnetic resonance/DNP spectrometer at 80 kelvins. We envisage that DNP echoes will play an important role in future development of pulsed DNP for sensitivity-enhanced nuclear magnetic resonance, hyperfine spectroscopy, and quantum sensing.

Figures

12 panels with data across 1 figure. Each panel page shows the plot, its columns and its files; each data.csv begins with a header naming the paper, the panel, the source, the license and the provenance route.

Fig. 1

Illustrative figure, no extractable data. Shown in the paper PDF.

Fig. 2

• panel (a-1): NMR signal (bulk proton polarization read out by a solid echo) against the total DNP time $t$, for the reference sequence with no phase inversion ($t_{\mathrm{inv}} = 0$). Top plot of panel (A). The trace runs past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (a-2): EPR signal (electron polarization read out by a Hahn echo) against the total DNP time $t$, for the reference sequence with no phase inversion ($t_{\mathrm{inv}} = 0$). Bottom plot of panel (A). The trace runs past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (b-1): NMR signal (bulk proton polarization read out by a solid echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 132$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Top plot of panel (B). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (b-2): EPR signal (electron polarization read out by a Hahn echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 132$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Bottom plot of panel (B). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (c-1): NMR signal (bulk proton polarization read out by a solid echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 220$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Top plot of panel (C). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (c-2): EPR signal (electron polarization read out by a Hahn echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 220$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Bottom plot of panel (C). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (d-1): NMR signal (bulk proton polarization read out by a solid echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 440$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Top plot of panel (D). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (d-2): EPR signal (electron polarization read out by a Hahn echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 440$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Bottom plot of panel (D). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (e-1): NMR signal (bulk proton polarization read out by a solid echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 880$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Top plot of panel (E). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (e-2): EPR signal (electron polarization read out by a Hahn echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 880$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Bottom plot of panel (E). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (f-1): NMR signal (bulk proton polarization read out by a solid echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 2200$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Top plot of panel (F). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv
• panel (f-2): EPR signal (electron polarization read out by a Hahn echo) against the total DNP time $t$ with the phase inverted at $t_{\mathrm{inv}} = 2200$ ns, with the $t_{\mathrm{inv}} = 0$ reference in grey and a dashed line at the expected echo position $t = 2t_{\mathrm{inv}}$. Bottom plot of panel (F). The traces run past the printed $t$ = 6 $\mu$s, shown here on the printed range. data.csv

Cite

Nino Wili, Anders B. Nielsen, José P. Carvalho, Niels Chr. Nielsen. Observation of dynamic nuclear polarization echoes. Sci. Adv. 10, eadr2420 (2024). https://doi.org/10.1126/sciadv.adr2420

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