Laser nanoablation of graphite

Experimental data on laser ablation of highly oriented pyrolitic graphite by nanosecond pulsed UV ( $\lambda =193$  nm) and green ( $\lambda =532$  nm) lasers are presented. It was found that below graphite vaporization threshold $\approx $ 1 J/cm $^{2}$ , the nanoablation regime can be realized with material removal rates as low as 10 $^{-3}$  nm/pulse. The difference between physical (vaporization) and physical–chemical (heating + oxidation) ablation regimes is discussed. Special attention is paid to the influence of laser fluence and pulse number on ablation kinetics. Possibility of laser-induced graphite surface nanostructuring has been demonstrated. Combination of tightly focused laser beam and sharp tip of scanning probe microscope was applied to improve material nanoablation.     

Laser-induced modification of bulk fused silica by femtosecond pulses

The features of the local nondestructive modifications of the bulk fused silica are experimentally studied. A method for the measurement of the refractive index in a transparent sample irradiated with femtosecond laser pulses is developed. The accuracy of the refractive-index measurements achieves about 10^?5, and a spatial resolution is several microns. The quantitative data on the dynamics of the permanent modification of glass as a function of the radiation energy are obtained for the first time. The spatial localization of the modified area that is predominantly determined by the laser-beam divergence is analyzed. The femtosecond interferometry is used to investigate the laser-pulse propagation in amorphous silica.     

Manipulations with diamond nanoparticles in SPM: the effect of electric field of the conductive probe tip

The role of the electric field during manipulations with diamond nanoparticles on a silicon substrate by a scanning probe microscope (SPM) tip is studied. It is found that the attractive force appearing in the contact between nanodiamond and an electrically charged tip is sufficient to detach and displace a chosen nanoparticle from initial to goal position under moderate mechanical stresses of the probe to nanoparticle. The problem of the control of the tip motion trajectory during manipulations is solved by visualizing the tip trace of the sample surface. The results obtained will be used for precision positioning of single-photon emitters based on luminescent nanodiamonds in microcavities.     

Effect of the surface state on pulsed laser etching of ultrananocrystalline nitrogen-doped diamond films

It is shown that the rate of laser oxidation of ultrananocrystalline films in the nanoablation mode is limited by the presence of physically and chemically adsorbed hydrogen-containing molecules on the surface and can be increased by preliminary thermal annealing. It is proposed to explain the observed saturation of the laser etching rate with the number of pulses by water molecule dissociation on the surface and film saturation with hydride and hydroxyl groups.     

Synthesis and doping of microcolumn diamond photoemitters with silicon-vacancy color centers

Bulletin of the Lebedev Physics Institute - The method of epitaxial growth of localized photoluminescence sources in the form of the ordered microcolumn diamond structures with silicon-vacancy...     

Microstructuring of diamond bulk by IR femtosecond laser pulses

We report the fabrication of graphitic microstructures in the bulk of chemical vapor deposited (CVD) diamond using 120-fs laser pulses at 800-nm wavelength. The nature of the laser-modified region and generation of mechanical stresses in the surrounding diamond is studied with Raman spectroscopy. A spontaneous growth of the laser-modified region from the focal plane towards the laser has been visualized in the process of multipulse irradiation with different pulse energies. The formation of discrete or continuous graphitized structures is revealed depending on the varied local laser intensity. The physical processes governing the appearance of separate graphitic globules and continuous extension of the graphitized region are discussed. Controlling the laser irradiation conditions permits us to fabricate graphitic wires with typical length of 150 μm and diameter of 1.5 μm. The longer, 300-ps pulses, as applied to laser microstructuring of the CVD diamond bulk, are found to be inappropriate due to the stronger influence of structural defects on the damage threshold, the noticeable fluctuation of the structure diameter over the length and the pronounced cracking of the surrounding diamond. PACS 42.62.-b; 61.80.Ba     

Effect of laser radiation parameters on the conductivity of structures produced on the polycrystalline diamond surface

Graphitized structures are fabricated on the polycrystalline diamond surface using an excimer KrF (λ = 248 nm, τ = 20 ns) and a Ti:Al₂O₃ (λ = 400 nm, τ = 120 fs) lasers. It is shown that the conductivity of formed structures is independent of the energy density and the number of pulses per surface point in the case of the excimer laser, whereas such a dependence was observed for femtosecond pulses. The causes of the dependence of the conductivity of surface structures on laser irradiation parameters are discussed.