2D-IR spectroscopy was used to characterize the vibrational dynamics of surface hydride modes on silicon nanoparticles (SiNPs). Energy transfer was compared between undoped (intrinsic) SiNPs and particles that were doped with boron and phosphorus. FTIR spectra reported changes in the relative proportions of Si-H, Si-H2, and Si-H3 populations when boron and phosphorus atoms were incorporated, while 2D-IR spectroscopy revealed that there was vibrational energy transfer on the tens of ps time scale between all three mode types for intrinsic SiNPs. This energy transfer was severely diminished by including just 0.05 atomic % of boron and was completely extinguished for 2.5 atomic % of phosphorus. In addition, the vibrational lifetimes of mono and polyhydride modes on intrinsic silicon particles were uniformly fast, while doped nanoparticles showed frequency dependent relaxation times reminiscent of porous and amorphous silicon films.
Bibliographical noteFunding Information:
The authors gratefully acknowledge funding from the National Science Foundation under CHE-0847356 and CHE-1464416. I.C.S. was supported by a National Science Foundation Graduate Student Research Fellowship 00039202. K.S.S. and U.R.K. were supported by the Army Office of Research under MURI Grant W911NF-12-1-0407. Parts of this work were carried out in the Minnesota Nano Center, which receives partial support from the NSF through the NNIN program.