A non-imaging concentrator for fiber optic mediated remote micro-Raman spectroscopy

The recent availability of moderate power near-infrared diode lasers (780nm) and near-infrared sensitive ccd detectors have caused a noticeable resurgence in the application of Raman spectroscopy in analytical chemistry. We have long maintained an interest in Raman spectroscopy and have established a micro-Raman facility within the Chemistry Department of our organization. Recently, we have taken advantage of the aforementioned progress in spectroscopic equipment and have upgraded our micro-Raman facility to include a ccd detector and an imaging spectrograph.Since our micro-Raman spectrometer is designed around an ellipsoidal collection mirror, with Raman signal being directed through the illumination sample stage it has application to microscopic or small transparent samples. The improved performance of the device and the availability of highly transmissive optical fibers led one of us (B.J.M.) to propose an apparatus that could replace the existing illuminator with a miniature device that maintains a high collection efficiency and can be used remotely or in-situ by utilizing optical fibers.

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In situ near infrared evanescent wave examination of surfactant adsorption on silica optical fibers

Composite Interfaces ◽

10.1163/156855494x00085 ◽

1994 ◽

Vol 2 (3) ◽

pp. 187-197 ◽

Cited By ~ 1

Author(s):

A.K. Liao ◽

W.M. Cross ◽

R.M. Winter ◽

J.J. Kellar

Keyword(s):

Optical Fibers ◽

Evanescent Wave ◽

Near Infrared ◽

Surfactant Adsorption

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Raman Signal Enhancement in Deep Spectroscopy of Turbid Media

Applied Spectroscopy ◽

10.1366/000370207781540178 ◽

2007 ◽

Vol 61 (8) ◽

pp. 845-854 ◽

Cited By ~ 49

Author(s):

P. Matousek

Keyword(s):

Raman Spectroscopy ◽

Laser Radiation ◽

Laser Beam ◽

Near Infrared ◽

Optical Element ◽

Disease Diagnosis ◽

Pharmaceutical Products ◽

Turbid Media ◽

Raman Signal

A new, passive method for enhancing spontaneous Raman signals for the spectroscopic investigation of turbid media is presented. The main areas to benefit are transmission Raman and spatially offset Raman spectroscopy approaches for deep probing of turbid media. The enhancement, which is typically several fold, is achieved using a multilayer dielectric optical element, such as a bandpass filter, placed within the laser beam over the sample. This element prevents loss of the photons that re-emerge from the medium at the critical point where the laser beam enters the sample, the point where major photon loss occurs. This leads to a substantial increase of the coupling of laser radiation into the sample and consequently an enhanced laser photon–medium interaction process. The method utilizes the angular dependence of dielectric optical elements on impacting photon direction with its transmission spectral profile shifting to the blue with increase in the deviation of photons away from normal incidence. This feature enables it to act as a unidirectional mirror passing a semi-collimated laser beam through unhindered from one side, and at the other side, reflecting photons emerging from the sample at random directions back into it with no restrictions to the detected Raman signal. With substantial restrictions to the spectral range, the concept can also be applied to conventional backscattering Raman spectroscopy. The use of additional reflective elements around the sample to enhance the Raman signal further is also discussed. The increased signal strength yields higher signal quality, a feature important in many applications. Potential uses include sensitive noninvasive disease diagnosis in vivo, security screening, and quality control of pharmaceutical products. The concept is also applicable in an analogous manner to other types of analytical methods such as fluorescence or near-infrared (NIR) absorption spectroscopy of turbid media or it can be used to enhance the effectiveness of the coupling of laser radiation into tissue in applications such as photodynamic therapy for cancer treatment.

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In situ determination of the complex permittivity of ultrathin H2-infused palladium coatings for plasmonic fiber optic sensors in the near infrared

Journal of Materials Chemistry C ◽

10.1039/c8tc01278d ◽

2018 ◽

Vol 6 (19) ◽

pp. 5161-5170 ◽

Cited By ~ 11

Author(s):

Xuejun Zhang ◽

Shunshuo Cai ◽

Fu Liu ◽

Hao Chen ◽

Peiguang Yan ◽

...

Keyword(s):

Optical Fibers ◽

Complex Permittivity ◽

Near Infrared ◽

Fiber Optic ◽

Fiber Optic Sensors

In situ determination of the complex permittivity of H2-infused palladium using near infrared plasmons over optical fibers.

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Improved performance of near infrared excitation Raman spectroscopy using reflective thin-film gold on glass substrates for cytology samples

Analytical Methods ◽

10.1039/c9ay01672d ◽

2019 ◽

Vol 11 (47) ◽

pp. 6023-6032

Author(s):

Sinead J. Barton ◽

Kevin O'Dwyer ◽

Marion Butler ◽

Adam Dignam ◽

Hugh J. Byrne ◽

...

Keyword(s):

Thin Film ◽

Raman Spectroscopy ◽

Near Infrared ◽

Signal To Noise Ratio ◽

Signal To Noise ◽

Glass Substrates ◽

Gold Substrates ◽

Infrared Excitation ◽

Improved Performance ◽

The Cost

Thin-film gold substrates offer improved performance and cost for NIR excitation Raman spectroscopy of biological cells when compared with CaF2. We demonstrate a 1.65 times enhancement in the signal to noise ratio with <5% of the cost.

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Application of FTIR and Raman Spectroscopy to Characterisation of Bioactive Materials and Living Cells

Spectroscopy An International Journal ◽

10.1155/2003/893584 ◽

2003 ◽

Vol 17 (2-3) ◽

pp. 275-288 ◽

Cited By ~ 55

Author(s):

I. Notingher ◽

J. R. Jones ◽

S. Verrier ◽

I. Bisson ◽

P. Embanga ◽

...

Keyword(s):

Raman Spectroscopy ◽

Near Infrared ◽

Cell Damage ◽

Living Cells ◽

Biologically Active ◽

Bioactive Materials ◽

45S5 Bioglass ◽

Ftir And Raman Spectroscopy

Both Fourier Transform Infrared (FTIR) and Raman spectroscopy have been applied to thein vitrocharacterisation of biomaterials, mainly surface reactions leading to the formation of a biologically active hydroxycarbonate apatite (HCA) layer on the sample surface when immersed in simulated body fluids (SBF). The HCA layer indicates the degree of bioactivity of the sample, because it leads to a strong bond between the biomaterial and living tissue. Reflection measurements using FTIR allow quick, non-destructive detection of the HCA layer for solid and powder samples. Due to the low Raman scattering efficiency and low absorption of water in the visible-near infrared region, Raman micro-spectroscopy was successfully used for thein situcharacterisation of 20 and 40µm diameter 45S5 Bioglass®fibres. Thein situcapabilities of the Raman micro-spectrometer have also been extended to the characterisation of living cells attached on bioinert silica and bioactive 45S5 Bioglass®and 58S substrates. Using a high power 785 nm laser, living cells in physiological conditions can be real-time sampled over long periods of time without inducing cell damage and with good signal strength. Cell death can be monitored because it proved to induce strong changes in the Raman signature in the spectral regions 1000–1150 cm–1and 1550–1650 cm–1.

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In-Line Near-Infrared (NIR) and Raman Spectroscopy Coupled with Principal Component Analysis (PCA) for in Situ Evaluation of the Transesterification Reaction

Applied Spectroscopy ◽

10.1366/12-06729 ◽

2013 ◽

Vol 67 (10) ◽

pp. 1142-1149 ◽

Cited By ~ 10

Author(s):

Miriam Fontalvo-Gómez ◽

José A Colucci ◽

Natasha Velez ◽

Rodolfo J. Romañach

Keyword(s):

Principal Component Analysis ◽

Raman Spectroscopy ◽

Near Infrared ◽

Principal Component ◽

Component Analysis ◽

Transesterification Reaction

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Single mode waveguide platform for spontaneous and surface-enhanced on-chip Raman spectroscopy

Interface Focus ◽

10.1098/rsfs.2016.0015 ◽

2016 ◽

Vol 6 (4) ◽

pp. 20160015 ◽

Cited By ~ 13

Author(s):

Ashim Dhakal ◽

Frédéric Peyskens ◽

Stéphane Clemmen ◽

Ali Raza ◽

Pieter Wuytens ◽

...

Keyword(s):

Raman Spectroscopy ◽

Collection Efficiency ◽

Single Mode ◽

Surface Enhanced Raman Spectroscopy ◽

Oxide Semiconductor ◽

Design Parameters ◽

Raman Signal ◽

Theoretical Concepts ◽

Surface Enhanced ◽

On Chip

We review an on-chip approach for spontaneous Raman spectroscopy and surface-enhanced Raman spectroscopy based on evanescent excitation of the analyte as well as evanescent collection of the Raman signal using complementary metal oxide semiconductor (CMOS)-compatible single mode waveguides. The signal is either directly collected from the analyte molecules or via plasmonic nanoantennas integrated on top of the waveguides. Flexibility in the design of the geometry of the waveguide, and/or the geometry of the antennas, enables optimization of the collection efficiency. Furthermore, the sensor can be integrated with additional functionality (sources, detectors, spectrometers) on the same chip. In this paper, the basic theoretical concepts are introduced to identify the key design parameters, and some proof-of-concept experimental results are reviewed.

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