Abstract
Abstract The objective of this research is mainly talking about the linear and nonlinear experimental studies on spectroscopic properties of the nitrogen□vacancy□nitrogen (NVN) and nitrogen□vacancy (N-V)- defect centers in type Ia and Ib diamond, and their related applications in this report are presented in four parts. The first part, we report the application of a multi-kHz diode-laser-pumped Q-switched Nd:YAG laser operating at 1064 nm to obtain two-photon-excited fluorescence scanning images with photolithography prepared photoresist film, red fluorescent polystyrene beads, R6G-dyed onion skin and also type Ib single crystal diamond. With careful and properly chosen operating parameters, we do not observe damages to the samples after repeated scans. The spatial resolution achieved was about 0.5 micron. The second part shows experimental results of one-photon (532nm) and two-photon (1064nm) excited fluorescence spectra of the negative charged nitrogen –vacancy (N-V)□□ defect centers in type Ib diamond, and also the deduced results of the corresponding one-photon and two-photon absorption cross sections are reported. Comparing the normalized spectral shapes recorded from one-photon and two-photon excitations, they are very similar except the photoionization effect of neutral (N-V)0 centers which yield 575nm ZPL and the accompanied vibronic band were more obvious under much more intense 1064 nm excitation. The third part concerns experimental results of one-photon excitation of another related nitrogen vacancy centers, the H3 (NVN) centers, usually can be found in type Ia diamond. This work demonstrate the one-photon (473nm) excited fluorescence spectrum, the estimated corresponding absorption cross sections, and also the alternative use of type Ia diamond nanoparticles in biological applications. The fourth part is focusing on more detail characterization understanding of H3 centers in type Ia diamond. We chose 405nm as an excitation wavelength to avoid fluorescence sideband contributed from (N-V)-□□ centers. Through stretched-exponential fitting of luminescence lifetime, help us to understand the complex property of type Ia diamond, and also through lifetime measurement correlated with color and polarization dichroism, we found that there is not much correlation between lifetime and the internal polarization property of type Ia diamond. This might because the high concentration of defect centers which produced by the helium beam irradiation and annealing treatment, some distinguishable internal properties of color centers will be washed off, reveals homogeneous optical properties. And the color dichroism result tells us that the major color center properties of type Ia nanodiamond are H3 centers.