We present a systematic angle-resolved polarized Raman spectroscopy(ARPRS)study of black phosphorus(BP)nanostructures formed via electrochemical sodium-and lithium-ion intercalation.Sodium intercalation leads to bundl...We present a systematic angle-resolved polarized Raman spectroscopy(ARPRS)study of black phosphorus(BP)nanostructures formed via electrochemical sodium-and lithium-ion intercalation.Sodium intercalation leads to bundles of densely packed,highly uniform phosphorene nanoribbons(PNRs)separated by parallel amorphous channels,whereas lithium intercalation results in shorter,irregular nanoribbon-like segments with lower aspect ratios.In both cases,six additional Raman peaks(P1-P6)appear alongside the three primary Raman-active modes of BP(A_(g)^(1),B_(2g),and A_(g)^(2)).These peaks are attributed to the amorphous regions,as confirmed by their isotropic angular dependence in ARPRS measurements.The three BP modes show pronounced angular variations that differ significantly between the two intercalated samples.In sodium-intercalated BP,A_(g)^(1)and A_(g)^(2)modes retain a dumbbell-like angular dependence under parallel polarization with enhanced anisotropy and reduced symmetry under crossed polarization.At the same time,the B_(2g)mode transitions from four-lobed(cloverleaf)polar plot to a butterfly-like one.In contrast,lithium-intercalated BP exhibits weaker anisotropy and less anisotropic features in the angular polar plots for all three modes.These differences reflect the sensitivity of phonon behavior to underlying nanostructure morphology.The vibrational frequencies density of states(FDOS)calculations attribute the B_(2g)mode change to phonon band folding and mode mixing in PNRs.This study demonstrates the power of ARPRS in probing phonon-structure relationships and highlights the influence of edge geometry and quantum confinement on phonon dispersion in PNRs.展开更多
基金supported by the U.S.Department of Energy,Office of Science,Basic Energy Sciences,under Award#DE-SC0024131.
文摘We present a systematic angle-resolved polarized Raman spectroscopy(ARPRS)study of black phosphorus(BP)nanostructures formed via electrochemical sodium-and lithium-ion intercalation.Sodium intercalation leads to bundles of densely packed,highly uniform phosphorene nanoribbons(PNRs)separated by parallel amorphous channels,whereas lithium intercalation results in shorter,irregular nanoribbon-like segments with lower aspect ratios.In both cases,six additional Raman peaks(P1-P6)appear alongside the three primary Raman-active modes of BP(A_(g)^(1),B_(2g),and A_(g)^(2)).These peaks are attributed to the amorphous regions,as confirmed by their isotropic angular dependence in ARPRS measurements.The three BP modes show pronounced angular variations that differ significantly between the two intercalated samples.In sodium-intercalated BP,A_(g)^(1)and A_(g)^(2)modes retain a dumbbell-like angular dependence under parallel polarization with enhanced anisotropy and reduced symmetry under crossed polarization.At the same time,the B_(2g)mode transitions from four-lobed(cloverleaf)polar plot to a butterfly-like one.In contrast,lithium-intercalated BP exhibits weaker anisotropy and less anisotropic features in the angular polar plots for all three modes.These differences reflect the sensitivity of phonon behavior to underlying nanostructure morphology.The vibrational frequencies density of states(FDOS)calculations attribute the B_(2g)mode change to phonon band folding and mode mixing in PNRs.This study demonstrates the power of ARPRS in probing phonon-structure relationships and highlights the influence of edge geometry and quantum confinement on phonon dispersion in PNRs.
