Raman Spectroscopy of Iranian Region Calcite Using Pulsed Laser: An Approach of Fluorescence Suppression by Time-Gating Method

Soleimaninejad, Hamid; Matroodi, Fatima; Tavassoli, Seyed Hassan

doi:10.1155/2013/254964

Cited by 7 publications

(8 citation statements)

References 24 publications

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“…This means that when short laser pulses are used for excitation, the Raman photons are emitted earlier than fluorescence photons and can be detected separately by means of ultrafast detectors. Long-living luminescence of minerals can be suppressed at a nanosecond (ns) timescale (Soleimaninejad et al, 2012), while short-living fluorescence of biological material makes it necessary to use picosecond (ps) time resolution to minimise the contribution of fluorescence (Everall et al, 1986). In this study we make use of a fast-gated (250 ps) intensified CCD camera in combination with low-energy 3-ps laser pulses from a 76-MHz Ti:sapphire laser system (Efremov et al, 2007).…”

Section: Theory Of Raman Spectroscopymentioning

confidence: 99%

Will Raman meet bacteria on Mars? An overview of the optimal Raman spectroscopic techniques for carotenoid biomarkers detection on mineral backgrounds

Hooijschuur

Verkaaik

Davies

et al. 2015

Netherlands Journal of Geosciences

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Raman spectroscopy appears to be an ideal technique for the initial detection of biomarkers, molecules that are potentially indicative of life on planetary bodies elsewhere in our solar system. Carotenoids are particularly useful biomarkers as they are used widely across the species, relatively resistant to breakdown and no inorganic source is known. They are used by microorganisms in their cell membranes for protection against UV radiation. In this paper we focus on the detection of carotenoids in microorganisms within a mineral matrix. We compare the Raman signatures of pure compounds with those of laboratory-made mixtures of β-carotene and minerals. Carotenoids covered by 2.5 mm of translucent calcite or 40 mm of transparent halite were detected using a conventional confocal Raman microscope. To improve sensitivity and hence detection levels, Raman measurements were successfully performed under resonant conditions. Raman analysis can be compromised by fluorescence interference. Data are presented to show how the contribution from the fluorescent background in the Raman spectra can be reduced when making use of gated detection in time-resolved Raman spectroscopy. Overall, this study demonstrates some of the potential of Raman spectroscopy as a method for the detection of (past) life signatures during future planetary missions without taking current technical limitations such as instrumental size into account as recent rapid technical developments suggest these limitations will be resolved in time.

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Section: Theory Of Raman Spectroscopymentioning

confidence: 99%

Will Raman meet bacteria on Mars? An overview of the optimal Raman spectroscopic techniques for carotenoid biomarkers detection on mineral backgrounds

Hooijschuur

Verkaaik

Davies

et al. 2015

Netherlands Journal of Geosciences

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“…The main aim of this time gating is to minimise the ambient light background, but it also suppresses very longlived luminescence (>100 ns) [23]. Mineral fluorescence lifetimes can range from nanoseconds to the microsecond range [24]. However, fluorescence of organic origin typically has lifetimes in the order of nanoseconds [25].…”

Section: Introductionmentioning

confidence: 99%

Distinguishing bacteria from minerals in a layered sample using time-resolved Raman spectroscopy and global analysis

Mooij

Stokkum

Davies

et al. 2022

J. Opt.

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Mars is one of the prime candidates in the search for extraterrestrial life. At the most comparable terrestrial Martian analogue sites, life often occurs in endolithic form; i.e., hiding below the surface. To detect biomarkers of endolithic life, the two most promising options are drilling or measuring through the surface, the latter being less invasive and preferable. Raman spectroscopy is an established chemical identification method, and advanced Raman modes have been developed for sub-surface analysis. Time-resolved Raman spectroscopy (TRRS), based on picosecond pulsed excitation and a gated intensified CCD detector, adds the capability of fluorescence suppression and depth selection. This paper focuses on the separation of layers with time differences that are much smaller than the 200 ps (FWHM) gating time of the detector. As an analogue for endolithic life on Mars, D. radiodurans bacteria were measured through a 2.5 mm and 7.5 mm top layer of translucent calcite. TRRS spectra were recorded in a backscattering geometry, while stepwise increasing the detector delay in 25 ps steps. Through both of these layers, the Raman spectrum of the bacteria’s carotenoids could be detected. Global analysis was used to model a complete time-resolved spectrum of the sample. Using this analysis, the signals could be separated into three components: mineral Raman, bacterial Raman and bacterial fluorescence. The model also corrects for gating differences across the horizontal axis of the ICCD camera. With this approach well-separated Raman spectra were obtained even for the 2.5-mm calcite layer despite the temporal separation of approximately 20 ps, which is much shorter than the 200 ps detector gating time. TRRS could be a suitable approach for non-invasive detection of extraterrestrial subsurface biomarkers.

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“…TRRS has been successfully used in a variety of research areas like biomedical (Iping Petterson et al, 2015) and forensic applications (Iping Petterson et al, 2011). Gated detection for planetary sciences can be used for different reasons, for example, fluorescence suppression (Soleimaninejad et al, 2012), day-time measurements (Misra et al, 2005), and stand-off measurements (Babin et al, 2011;Skulinova et al, 2014). The latter approach will also be used with the NASA SuperCam system, which is designed to yield a 100 ns time resolution .…”

Section: Introductionmentioning

confidence: 99%

Raman Spectroscopic Techniques for Planetary Exploration: Detecting Microorganisms through Minerals

Verkaaik¹,

Hooijschuur²,

Davies³

et al. 2015

Astrobiology

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Raman spectroscopy can provide highly specific chemical fingerprints of inorganic and organic materials and is therefore expected to play a significant role in interplanetary missions, especially for the search for life elsewhere in our solar system. A major challenge will be the unambiguous detection of low levels of biomarkers on a mineral background. In addition, these biomarkers may not be present at the surface but rather inside or underneath minerals. Strong scattering may prevent focusing deeper into the sample. In this paper, we report the detection of carotenoid-containing microorganisms behind mineral layers using time-resolved Raman spectroscopy (TRRS). Two extremophiles, the bacterium Deinococcus radiodurans and the cyanobacterium Chroococcidiopsis, were detected through translucent and transparent minerals using 440 nm excitation under resonance conditions to selectively enhance the detection of carotenoids. Using 3 ps laser pulses and a 250 ps gated intensified CCD camera provided depth selectivity for the subsurface microorganisms over the mineral surface layer and in addition lowered the contribution of the fluorescent background. Raman spectra of both organisms could be detected through 5 mm of translucent calcite or 20 mm of transparent halite. Multilayered mineral samples were used to further test the applied method. A separate tunable laser setup for resonance Raman and a commercial confocal Raman microscope, both with continuous (non-gated) detection, were used for comparison. This study demonstrates the capabilities of TRRS for the depth-selective analysis through scattering samples, which could be used in future planetary exploration to detect microorganisms or biomarkers within or behind minerals.

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Raman Spectroscopy of Iranian Region Calcite Using Pulsed Laser: An Approach of Fluorescence Suppression by Time-Gating Method

Cited by 7 publications

References 24 publications

Will Raman meet bacteria on Mars? An overview of the optimal Raman spectroscopic techniques for carotenoid biomarkers detection on mineral backgrounds

Will Raman meet bacteria on Mars? An overview of the optimal Raman spectroscopic techniques for carotenoid biomarkers detection on mineral backgrounds

Distinguishing bacteria from minerals in a layered sample using time-resolved Raman spectroscopy and global analysis

Raman Spectroscopic Techniques for Planetary Exploration: Detecting Microorganisms through Minerals

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