Effect of pulse repetition rate and number of pulses in the analysis of polypropylene and high density polyethylene by nanosecond infrared laser induced breakdown spectroscopy

Abstract

Pulse repetition rates and the number of laser pulses are among the most important parameters that do affect the analysis of solid materials by laser induced breakdown spectroscopy, and the knowledge of their effects is of fundamental importance for suggesting analytical strategies when dealing with laser ablation processes of polymers. In this contribution, the influence of these parameters in the ablated mass and in the features of craters was evaluated in polypropylene and high density polyethylene plates containing pigment-based PbCrO 4. Surface characterization and craters profile were carried out by perfilometry and scanning electron microscopy. Area, volume and profile of craters were obtained using Taylor Map software. A laser induced breakdown spectroscopy system consisted of a Q-Switched Nd:YAG laser (1064 nm, 5 ns) and an Echelle spectrometer equipped with ICCD detector were used. The evaluated operating conditions consisted of 10, 25 and 50 laser pulses at 1, 5 and 10 Hz, 250 mJ/pulse (85 J cm −2), 2 s delay time and 6 s integration time gate. Differences in the topographical features among craters of both polymers were observed. The decrease in the repetition rate resulted in irregular craters and formation of edges, especially in polypropylene sample. The differences in the topographical features and ablated masses were attributed to the influence of the degree of crystallinity, crystalline melting temperature and glass transition temperature in the ablation process of the high density polyethylene and polypropylene. It was also observed that the intensities of chromium and lead emission signals obtained at 10 Hz were two times higher than at 5 Hz by keeping the number of laser pulses constant.

Direct chemical inspection of eye shadow and lipstick solid samples using laser-induced breakdown spectroscopy (LIBS) and chemometrics: proposition of classification models

“…The most favorable experimental conditions for LIBS analyses on eye shadow and lipstick were selected after performing a 2 3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Analytical Methods Accepted Manuscript 12 A PCA was performed using the mean centered data (no further preprocessing was performed on the data set), and 8 classes were taken into consideration: color (13 different color levels), origin (Brazil, the USA and China), brands (10 different brands), price (2 different unitary ranges of price), specific characteristics (opaque and brilliant), intended user (adults and children), type (eye shadow and lipstick) and legislation (below and above 5 mg kg -1 , see Table 1). …”

Plastic identification based on molecular and elemental information from laser induced breakdown spectra: a comparison of plasma conditions in view of efficient sorting

“…It is also a current issue of laser induced breakdown spectroscopy (LIBS). If LIBS remained long a technique strictly dedicated to the determination of the inorganic elements, some works deal now with the determination of organics employing the rich LIBS spectra [3][4][5][6].…”

Quantitative elemental analysis of polymers through laser ablation – inductively coupled plasma by using a dried droplet calibration approach, DDCA

“…11,15,16,17 Unfortunately, the sample ablation yield depends strongly on the type of polymer and, hence, it is still difficult to find suitable solid standards. 10,18,19 In order to compensate for changes in the sample ablated mass as a function of the matrix, 20 an element acting as internal standard (IS) can be selected. 20,21[ Carbon has been suggested as a good candidate because of its known concentration in polymers and its uniform distribution within the samples.…”