Plasma characterization during laser ablation of graphite in nitrogen for the growth of fullerene-like CNx films

Abstract

Articles you may be interested inFeasibility of characterizing laser-ablated carbon plasmas via planar laser induced fluorescencea) Rev. Sci. Instrum. 83, 10E515 (2012); 10.1063/1.4733562Spatio-temporal mapping of ablated species in ultrafast laser-produced graphite plasmas Growth and structure of fullerene-like CN x thin films produced by pulsed laser ablation of graphite in nitrogen Chemistry, energy, and spatial distributions of species in carbon-nitrogen plasma plumes were investigated to define plasma conditions for growth of carbon nitride CN x films with a fullerene-like structure. Plumes were generated by ablation of graphite using a 248 nm excimer laser in the presence of low-pressure nitrogen. The plumes were investigated using element specific imaging, time-of-flight experiments, fluorescence spectroscopy, and molecular vibration sequence analyses. Studies showed the importance of plume/substrate interaction in causing secondary excitation phenomena. For N 2 pressures within the 5-50 mTorr range, plasmas at the substrate vicinity were found to consist mostly of atomic carbon, CN and C 2 molecules. Kinetic energies were calculated within 10-20 eV for mono atomic carbon, 30-55 eV for CN, and 20-40 eV for C 2 . Excited CN and C 2 molecules were generated by laser ablation and by collisions of the plume with the substrate surface. Their vibrational energies were strongly influenced by nitrogen pressure and time after a laser pulse. For pressures below 30 mTorr, vibrational energy was as high as 4.0 eV at 2-4 s for CN and 2.5 eV at 8 -10 s for C 2 . This low pressure was suggested for the growth of fullerene-like CN x films based on correlations between plasma parameters and film composition and bonding. Synthesis of the fullerene-like structure required high molecular temperatures at the condensation surface. High concentrations of CN radicals in the plasma promoted nitrogen incorporation into the films. Correlations among CN x film composition/bonding, excitation maximums, and kinetic/ vibrational energies of atomic carbon, CN and C 2 species located near the condensation surface are discussed.

Microphysical properties of carbonaceous aerosol particles generated by laser ablation of a graphite target

“…However, this study only serves to demonstrate the variability of the presented methodology regardless of the detailed investigation of the gas to particle interaction during the particle formation, i.e., contamination of the generated particles by the composition of purging gases; therefore, further studies are needed to investigate the possibilities and advantages of using other types of purging gases. Further studies are needed to investigate the possibilities and advantages of using other types of purging gases, i.e., using argon to avoid the nitrogen contamination of the generated primary particles (Voevodin et al, 2002;Ritikos et al, 2011;Yang et al, 2007).…”

In Situ Spectroscopic Analysis of the Carbothermal Reduction Process of Iron Oxides during Microwave Irradiation

“…The measurement conditions of the emission spectra and photograph are listed in Table 1. Line spectra were assigned based on the literature [20][21][22][23]. After microwave irradiation, the pellet was ground, and the phases were analyzed by XRD.…”

Plasma characterization of pulsed-laser ablation process used for fullerene-like CNx thin film deposition

“…On the other hand, because the average energy of laser-ablated species is much higher than kT and a certain fraction of these species is ionized, it is possible to form metastable phases such as diamondlike carbon (DLC) and fullerene-like amorphous carbon nitride, CNx, materials from a graphite target in nitrogen atmospheres [1,3]. For this reason, laser-ablated carbon plumes have been widely characterized.…”

“…Among the various diagnostic techniques, which are convenient tools in the detection of different chemical species, the OES has remarkable advantages appertaining to high spatial and temporal resolution for in situ characterization without perturbation of the plasma. From the intensities and contour forms of the observed emission spectra in the OES, useful plasma parameters such as: electron temperature and density [9], kinetic energy of ablated species, and vibrational temperature of molecules can be estimated [1][2][3][4]. This work analyzes plasma chemistry, physics, and vibrational temperature of CN and C 2 species present in the plume close to the target surface.…”

“…Since the dynamic behaviour of species in the laser-ablated plasma plume affects the characteristic of deposited thin films, many publications aim to understand the PLD process and the correlation between composition, structure, and properties of deposited films, plasma parameters, and chemical state of species present in the plasma [1][2][3]. Different techniques such as Optical Emission Spectroscopy (OES) [1,3,4], time-offlight mass spectroscopy [1,3,5], laser-induced fluorescence spectroscopy [6], interferometry [7], and Langmuir probe method [8] have been used in order to understand and control the deposition process. Among the various diagnostic techniques, which are convenient tools in the detection of different chemical species, the OES has remarkable advantages appertaining to high spatial and temporal resolution for in situ characterization without perturbation of the plasma.…”