Two photon excited fluorescence from diamond nanoparticles

The possibility of two photon eaxcited fluorescence by diamond nanoparticles is an interesting nonlinear phenomenon. We have grown 20-100 nm diamond nanoparticles by using chemical vapor deposition (CVD) and characterized their properties by using complementary techniques of AFM, SEM, and Raman spectroscopy.\footnote{R. Chakraborty, S. C. Sharma, and J. K. LaRoque, J. Nano Research, \textbf{12}, 1123 (2010)}$^,$\footnote{R. Chakraborty and S. C. Sharma, Physica B, \textbf{406}, 4170 (2011)} In this work, we have utilized femtosecond laser based two-photon excitation to study the emission of visible light ($\sim$ 530 nm) as functions of the excitation wavelength (750-850 nm), excitation power, and size of the NPs. These results and their potential applications will be discussed.