Time-resolved characterization of laser-induced plasma from fresh potatoes

详细信息    查看全文

• 作者：Wenqi Lei ; Vincent Motto-Ros ; Myriam Boueri ; Qianli Ma ; Dacheng Zhang ; Lijuan Zheng ; Heping Zeng ; Jin Yu
• 关键词：Laser ablation ; Plasma diagnostics ; LIBS ; Trace elements ; Vegetables
• 刊名：Spectrochimica Acta Part B: Atomic Spectroscopy
• 出版年：2009
• 出版时间：September 2009
• 年：2009
• 卷：64
• 期：9
• 页码：891-898
• 全文大小：477 K

文摘

Optical emission of laser-induced plasma on the surface of fresh vegetables provides sensitive analysis of trace elements for in situ or online detection of these materials. This emergent technique promises applications with expected outcomes in food security or nutrition quality, as well as environment pollution detection. Characterization of the plasma induced on such soft and humid materials represents the first step towards quantitative measurement using this technique. In this paper, we present the experimental setup and protocol that optimize the plasma generation on fresh vegetables, potatoes for instance. The temporal evolution of the plasma properties are investigated using time-resolved laser-induced breakdown spectroscopy (LIBS). In particular, the electron density and the temperatures of the plasma are reported as functions of its decay time. The temperatures are evaluated from the well known Boltzmann and Saha-Boltzmann plot methods. These temperatures are further compared to that of the typical molecular species, CN, for laser-induced plasma from plant materials. This comparison validates the local thermodynamic equilibrium (LTE) in the specific case of fresh vegetables ablated in the typical LIBS conditions. A study of the temporal evolution of the signal to noise ratio also provides practical indications for an optimized detection of trace elements. We demonstrate finally that, under certain conditions, the calibration-free LIBS procedure can be applied to determine the concentrations of trace elements in fresh vegetables.