Fig. 4: Contribution of quantum tunneling to the CDSE of Au NPoM/OS system.

a Configurations of double and single helices of OS-1, OS-2, and OS-3. The sizes are based on modeling by SPARTAN. b Schematic of Au NPoM/OS before and after heating, showing decreased gap size. c Change of plasmon resonances with gap size. The background mapping is the simulated scattering spectra of Au NPoM at different gap sizes based on QCM. The pink, green, and blue arrows represent the experimental data of plasmon resonance change with gap size after heating OS-1, OS-2 and OS-3, respectively. The data points are averaged and statistically plotted over 30 Au NPoMs and the gray dash line serves as the guide for eyes only. The gray sold line is the calculated change of plasmon resonance with gap size based on the circuit model. The error bars are the standard deviation of plasmon peaks. d Averaged CDS spectra of Au NPoM/OS in the state of DH and SH. The light blue and pink bands represent the standard deviation of 10 CDS spectra in each case. e Change of the absolute CDS intensity (dips around 750 nm) extracted from d (red dash line) and calculated CDSE (green and blue dash lines) with gap size. The green and blue dots represent the CDSE calculated with QCM and CM, respectively. The black dash line highlights the transition from CR to QR. The error bars are the standard deviation of CDS intensities at different gap sizes.