Laser Induced Breakdown Spectroscopy for Analysis of Aerosols

Diwakar, Prasoon K.; Kulkarni, Pramod

doi:10.1007/978-3-642-45085-3_9

Cited by 4 publications

(1 citation statement)

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“…We did not conduct detailed investigation of the needle lifetime in this study. However, in another ongoing study (Diwakar and Kulkarni 2011), where pulsed spark plasma is used, instead of the laser plasma, along with identical electrode setup, we did investigate the electrode durability. Pulsed spark plasma energy in the range of 150-300 mJ/pulse, much higher than the laser energy of 20 mJ/pulse used in this study, was employed.…”

Section: Laser-needle Orientation Effectsmentioning

confidence: 99%

New Approach for Near-Real-Time Measurement of Elemental Composition of Aerosol Using Laser-Induced Breakdown Spectroscopy

Diwakar

Kulkarni

Birch

2012

Aerosol Science and Technology

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A new approach has been developed for making near-real-time measurement of elemental composition of aerosols using plasma spectroscopy. The method allows preconcentration of miniscule particle mass (pg to ng) directly from the sampled aerosol stream through electrostatic deposition of charged particles (30-900 nm) onto a flat-tip microneedle electrode. The collected material is subsequently ablated from the electrode and monitored by laserinduced breakdown spectroscopy. Atomic emission spectra were collected using a broadband spectrometer with a wavelength range of 200-980 nm. A single-sensor delay time of 1.3 µs was used in the spectrometer for all elements to allow simultaneous measurement of multiple elements. The system was calibrated for various elements including Cd, Cr, Cu, Mn, Na, and Ti. The absolute mass detection limits for these elements were experimentally determined and found to be in the range of 0.018-5 ng. The electrostatic collection technique has many advantages over other substrate-based methods involving aerosol collection on a filter or its focused deposition using an aerodynamic lens. Because the particle mass is collected over a very small area that is smaller than the spatial extent of the laser-induced plasma, the entire mass is available for analysis. This considerably improves reliability of the calibration and enhances measurement accuracy and precision. Further, the aerosol collection technique involves very low pressure drop, thereby allowing higher sample flow rates with much smaller pumps-a desirable feature for portable instrumentation. Higher flow rates also make it feasible to measure trace element concentrations at part per trillion levels. Detection limits in the range of 18-670 ng m −3 can be achieved for most of the elements studied at a flow rate of 1.5 L min −1 with sampling times of 5 min.

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Section: Laser-needle Orientation Effectsmentioning

confidence: 99%