Laser heating versus phonon confinement effect in the Raman spectra of diamond nanoparticles

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology Vol. 14; no. 6
• Main Authors: Chaigneau, Marc, Picardi, Gennaro, Girard, Hugues A., Arnault, Jean-Charles, Ossikovski, Razvigor
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.06.2012; Springer Verlag
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed Matter; Inorganic Chemistry; Lasers; Materials Science; Nanotechnology; Optical Devices; Optics; Photonics; Physical Chemistry; Physics; Research Paper; Quantum confinement; Diamond; Raman spectroscopy; Nanoparticle; Laser beam effects; Diamond Nanoparticle
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-012-0955-9

Nanodiamond particles with typical diameters of 20 and 6 nm produced by high pressure high temperature or detonation processes have been studied by micro-Raman spectroscopy. We show that the frequency downshift and broadening of the first-order diamond phonon band is not uniquely related to phonon confinement, as commonly assumed. Local heating caused by the focused laser light must be also taken in account, since it may affect the Raman spectrum in a similar fashion, even at relatively low laser power levels. A combined theoretical model considering both effects (quantum confinement and local heating) on the excited phonon modes is presented and adopted for the simulation of the experimental data. We observe different heating behaviours upon laser illumination depending on the particles origin, thus underscoring the importance to compensate for this effect before retrieving structural parameters.