Photoluminescence of Nitrogen-Vacancy Centers by Ultraviolet One- and Two-Photon Excitation of Fluorescent Nanodiamonds
Journal
Journal of Physical Chemistry Letters
Journal Volume
13
Journal Issue
48
Date Issued
2022-12-08
Author(s)
Yang, Teng I.
Huang, Yu Wen
Bista, Prabesh
Chen, Jeson
Chiang, Cheng Tien
Chang, Huan Cheng
Abstract
Fluorescent nanodiamonds contain nitrogen-vacancy (NV) centers as quantum defects. When exposed to a continuous-wave 325 nm laser or a femtosecond 344 nm laser, the particles emit red fluorescence from NV0 centers at ∼620 nm. Power dependence measurements of the emission strength revealed a predominantly linear behavior at the laser peak intensity lower than 1 GW·cm-2, contributed mainly by photoexcitation of electrons from the valence band of diamond to the NV0 centers, followed by relaxation via electron-hole recombination. In the higher power regions, however, nonresonant two-photon interband excitation of the diamond matrix dominates the photoluminescence processes. Best fits of the experimental data to semiempirical models revealed an ionization coefficient of ∼1 cm-1 for the one-photon valence-to-defect excitation and a saturation intensity of 180 ± 60 GW·cm-2 for the two-photon interband excitation. The study provides new insight into the photoionization of NV0 centers and the interband excitation properties of diamond in the UV region.
Type
journal article