We are in the initial stages of analyzing plasma produced by the laser induced ablation of Titanium Dioxide. Time resolved and space resolved optical emission spectroscopy were performed and time integrated analysis was used to compute the parameters like electron temperature, density and velocity of species.

The experimental setup consists of a nanosecond laser system (Quanta-Ray, DCR 11) delivering 300mJ of power at a pulse duration of 10ns. This is capable of producing laser fluence of ~1010Wcm-2. A high resolution monochromator (1m SPEX) and a thermoelectrically cooled PMT are used for light detection during time resolved measurements. The time resolved detector used is a gated integrator and boxcar averager (SR 250). The boxcar gate width and monochromator slit width are optimized to maximize the spectral line intensity while maintaining good temporal resolution. An optical system consisting of two lenses of equal focal length is used to produce a one to one image slice of the plume, for spectroscopic diagnostics. The steel plasma chamber has two separate windows for examining plasma and leads for taking electrical connections and insertion of probe. The targets are placed inside the chamber, on a support linked to a motorized rotation system, in order to provide a fresh surface for ablation. A CCD detector (Roper scientific, NTE/CCD - 1340/100 - EM) coupled to the exit port of the spectrograph (Acton Research, Spectra Pro 500i) is used to record the spectral details collected for the time integrated measurements.

A triple peak distribution exhibited by the TOF profile of Ti is observed above a threshold pump power in TiO₂ plasma. The evolution of the peaks is studied for various laser irradiances. Their dependence on the distance from the target surface as shown in figure 1 provides some information about their origin. The different peaks are arising from Ti produced by different processes.


Within the range of laser fluence and temperature studied, excited atomic species and TiII are prominent. Spectral lines of oxygen or no molecular species are observed. At a spatial point 1mm from the target, the most populated section of LIP emerges after 90ns (figure 2). Variation of electron density and electron temperature obtained via, both time integrated and time resolved spectroscopic techniques is tested for the validity of LTE and is found to satisfy the necessary criterion for LTE.

The spatial and temporal distribution of fundamental plasma parameters such as electron density, electron temperature, electron and ion velocities during the laser ablation of ZnO target under various experimental conditions is also studied. In addition correlation between the plasma parameters and the properties of the ZnO thin film formed under similar plasma conditions are also being analyzed.