Advanced Centre of Research in High Energy Materials (ACRHEM)

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Browsing Advanced Centre of Research in High Energy Materials (ACRHEM) by Author "Barman, Ishan"
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    Identification of post-consumer plastics using laser-induced breakdown spectroscopy
    ( 2019-07-01) Junjuri, Rajendhar ; Zhang, Chi ; Barman, Ishan ; Gundawar, Manoj Kumar
    We report an accurate recognition of ten different types of postconsumer plastics, including five extensively used basic plastics, by laser-induced breakdown spectroscopy (LIBS). Ratiometric and correlational analysis have been performed for the classification in which C/H ratio yielded partial discrimination while an excellent correlation has been observed between the intensity of the carbon peak with carbon single bonds. Additionally, a 3D correlational approach using the emission intensities of carbon, hydrogen, oxygen and nitrogen lines successfully segregated all the plastics. Finally, we report findings from partial least squares- discriminant analysis (PLS-DA) that demonstrates classification accuracies of over 93 %. We envision that the high classification accuracy is shown here will encourage further validation studies leading to routine application of LIBS for screening and identification of post-consumer plastics.
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    Non-gated laser induced breakdown spectroscopy provides a powerful segmentation tool on concomitant treatment of characteristic and continuum emission
    ( 2014-08-01) Myakalwar, Ashwin Kumar ; Dingari, Narahara Chari ; Dasari, Ramachandra Rao ; Barman, Ishan ; Gundawar, Manoj Kumar
    We demonstrate the application of non-gated laser induced breakdown spectroscopy (LIBS) for characterization and classification of organic materials with similar chemical composition. While use of such a system introduces substantive continuum background in the spectral dataset, we show that appropriate treatment of the continuum and characteristic emission results in accurate discrimination of pharmaceutical formulations of similar stoichiometry. Specifically, our results suggest that near-perfect classification can be obtained by employing suitable multivariate analysis on the acquired spectra, without prior removal of the continuum background. Indeed, we conjecture that pre-processing in the form of background removal may introduce spurious features in the signal. Our findings in this report significantly advance the prior results in time-integrated LIBS application and suggest the possibility of a portable, non-gated LIBS system as a process analytical tool, given its simple instrumentation needs, real-time capability and lack of sample preparation requirements. © 2014 Myakalwar et al.
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    Real-time fingerprinting of structural isomers using laser induced breakdown spectroscopy
    ( 2016-05-21) Myakalwar, Ashwin Kumar ; Anubham, Siva Kumar ; Paidi, Santosh Kumar ; Barman, Ishan ; Gundawar, Manoj Kumar
    Laser induced breakdown spectroscopy (LIBS) has surfaced as an attractive alternative to mass spectrometry and wet chemistry methods for chemical identification, driven by its real-time, label-free nature. Rapid analysis needs, especially in high-energy materials and pharmaceutical compounds, have further fueled an increasing number of refinements in LIBS. Yet, isomers are seldom identifiable by LIBS as they generate nearly identical spectra. Here we employ a suite of chemometric approaches to exploit the subtle, but reproducible, differences in LIBS spectra acquired from structural isomers, a set of pyrazoles, to develop a sensitive and reliable segmentation method. We also investigate the possible mechanistic principles (causation) behind such spectral variations and confirm their statistically significant nature that empowers the excellent classification performance.