Ultra-spatially resolved synchrotron powered FT-IR microspectroscopy of individual cells of biological material

Synchrotron radiation is 100 to 1000 times brighter than a thermal source such as a globar. It is not accompanied with thermal noise and it is highly directional and nondivergent. For these reasons, it is well suited for ultra-spatially resolved FT-IR microspectroscopy. In efforts to attain good spatial resolution in FT-IR microspectroscopy with a thermal source, a considerable fraction of the infrared beam focused onto the specimen is lost when projected remote apertures are used to achieve a small spot size. This is the case because of divergence in the beam from that source. Also the brightness is limited and it is necessary to compromise on the signal-to-noise or to expect a long acquisition time from coadding many scans. A synchrotron powered FT-IR Microspectrometer does not suffer from this effect. Since most of the unaperatured beam’s energy makes it through even a 12 × 12 μm aperture, that is a starting place for aperture dimension reduction.

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FT-IR microspectroscopic analysis of diseased white matter brain tissues

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141214 ◽

1995 ◽

Vol 53 ◽

pp. 968-969

Author(s):

Steven M. Le Vine ◽

David L. Wetzel

Keyword(s):

White Matter ◽

Gray Matter ◽

Twitcher Mouse ◽

Grid Pattern ◽

Marked Contrast ◽

Spatially Resolved ◽

Ft Ir ◽

Ir Microspectroscopy ◽

Chemical Evidence

In situ FT-IR microspectroscopy has allowed spatially resolved interrogation of different parts of brain tissue. In previous work the spectrrscopic features of normal barin tissue were characterized. The white matter, gray matter and basal ganglia were mapped from appropriate peak area measurements from spectra obtained in a grid pattern. Bands prevalent in white matter were mostly associated with the lipid. These included 2927 and 1469 cm-1 due to CH2 as well as carbonyl at 1740 cm-1. Also 1235 and 1085 cm-1 due to phospholipid and galactocerebroside, respectively (Figs 1and2). Localized chemical changes in the white matter as a result of white matter diseases have been studied. This involved the documentation of localized chemical evidence of demyelination in shiverer mice in which the spectra of white matter lacked the marked contrast between it and gray matter exhibited in the white matter of normal mice (Fig. 3).The twitcher mouse, a model of Krabbe’s desease, was also studied. The purpose in this case was to look for a localized build-up of psychosine in the white matter caused by deficiencies in the enzyme responsible for its breakdown under normal conditions.

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Spatially Resolved Improved FT–IR Microspectroscopy of Deuterated Species in Tissue

Microscopy and Microanalysis ◽

10.1017/s1431927602104132 ◽

2002 ◽

Vol 8 (S02) ◽

pp. 1498-1499

Author(s):

David L. Wetzel ◽

Steven M. LeVine

Keyword(s):

Spatially Resolved ◽

Ft Ir ◽

Ir Microspectroscopy

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Spatially Resolved Improved FT–IR Microspectroscopy of Deuterated Species in Tissue

Microscopy and Microanalysis ◽

10.1017/s1431927602104144 ◽

2002 ◽

Vol 8 (S02) ◽

pp. 1502-1503

Author(s):

David L. Wetzel ◽

Steven M. LeVine

Keyword(s):

Spatially Resolved ◽

Ft Ir ◽

Ir Microspectroscopy

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Vibrational Stark Spectroscopy of Fluorobenzene Using Quantum Cascade Laser Dual Frequency Combs

Applied Spectroscopy ◽

10.1177/0003702819888503 ◽

2019 ◽

Vol 74 (3) ◽

pp. 347-356 ◽

Cited By ~ 1

Author(s):

Urszula Szczepaniak ◽

Samuel Hayes Schneider ◽

Raphael Horvath ◽

Jacek Kozuch ◽

Markus Geiser

Keyword(s):

Quantum Cascade Laser ◽

Signal To Noise Ratio ◽

Spectral Response ◽

Acquisition Time ◽

Dual Frequency ◽

Stark Spectroscopy ◽

Signal To Noise ◽

Quantum Cascade ◽

Ft Ir ◽

Noise Ratio

We demonstrate the performance of a dual frequency comb quantum cascade laser (QCL) spectrometer for the application of vibrational Stark spectroscopy. Measurements performed on fluorobenzene with the dual-comb spectrometer (DCS) were compared to results obtained using a conventional Fourier transform infrared (FT-IR) instrument in terms of spectral response, parameter estimation, and signal-to-noise ratio (S/N). The dual-comb spectrometer provided similar qualitative and quantitative data as the FT-IR setup in 250 times shorter acquisition time. For fluorobenzene, the DCS measurement resulted in a more precise estimation of the fluorobenzene Stark tuning rate ((0.81 ± 0.09) cm−1/(MV/cm)) than with the FT-IR system ((0.89 ± 0.15) cm−1/(MV/cm)). Both values are in accordance with the previously reported value of 0.84 cm−1/(MV/cm). We also point to an improvement of signal-to-noise ratio in the DCS configuration. Additional characteristics of the dual-comb spectrometer applicable to vibrational Stark spectroscopy and their scaling properties for future applications are discussed.

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Synchrotron powered FT-IR microspectroscopy permits small spot ATR sampling of fiber finish and other materials

10.1063/1.55747 ◽

1998 ◽

Cited By ~ 2

Author(s):

David L. Wetzel ◽

John A. Reffner ◽

G. Lawrence Carr ◽

Liling Cho

Keyword(s):

Small Spot ◽

Ft Ir ◽

Ir Microspectroscopy

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Characterization of Colorectal Adenocarcinoma Sections by Spatially Resolved FT-IR Microspectroscopy

Applied Spectroscopy ◽

10.1366/0003702021954322 ◽

2002 ◽

Vol 56 (1) ◽

pp. 1-9 ◽

Cited By ~ 71

Author(s):

Peter Lasch ◽

Wolfgang Haensch ◽

E. Neil Lewis ◽

Linda H. Kidder ◽

Dieter Naumann

Keyword(s):

Colorectal Adenocarcinoma ◽

Clinical Analysis ◽

Tissue Samples ◽

Spatially Resolved ◽

Ft Ir ◽

Ir Microspectroscopy ◽

Artificial Neural ◽

Tissue Specimens ◽

Spectral Databases

A combination of Fourier transform infrared (FT-IR) spectroscopy and microscopy, FT-IR microspectroscopy, has been used to characterize sections of human colorectal adenocarcinoma. In this report, a database of 2601 high quality FT-IR point spectra from 26 patient samples and seven different histological structures was recorded and analyzed. The computer-based analysis of the IR spectra was carried out in four steps: (1) an initial test for spectral quality, (2) data pre-processing, (3) data reduction and feature selection, and (4) classification of the tissue spectra by multivariate pattern recognition techniques such as hierarchical clustering and artificial neural network analysis. Furthermore, an example of how spectral databases can be utilized to reassemble false color images of tissue samples is presented. The overall classification accuracy attained by optimized artificial neural networks reached 95%, highlighting the great potential of FT-IR microspectroscopy as a potentially valuable, reagent-free technique for the characterization of tissue specimens. However, technical improvements and the compilation of validated spectral databases are essential prerequisites to make the infrared technique applicable to routine and experimental clinical analysis.

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Information capacity and bandwidth limitations in the SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152392 ◽

1989 ◽

Vol 47 ◽

pp. 84-85

Author(s):

D. C. Joy ◽

R. D. Bunn

Keyword(s):

Signal To Noise Ratio ◽

Critical Dimension ◽

Information Capacity ◽

Acquisition Time ◽

Signal To Noise ◽

Sem Image ◽

Probe Size ◽

Minimum Number ◽

Noise Ratio ◽

Signal Channel

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :

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A Comparison of FT-IR/PA and FT-IR/PBD Spectra of Powders

Applied Spectroscopy ◽

10.1366/0003702864508539 ◽

1986 ◽

Vol 40 (5) ◽

pp. 636-641 ◽

Cited By ~ 5

Author(s):

P. G. Varlashkin ◽

M. J. D. Low ◽

G. A. Parodi ◽

C. Morterra

Keyword(s):

Probe Beam ◽

Beam Deflection ◽

Signal To Noise ◽

Absorption Bands ◽

Ir Radiation ◽

Laser Probe ◽

Ft Ir ◽

Better Than

FT-IR photoacoustic (PA) and also photothermal beam deflection (PBD) spectra were recorded with the same particulate samples (graphite, charcoal, aspirin, and silica) under the same conditions in order to compare the quality of the spectra obtainable with the two techniques. A PA cell fitted with windows for the PBD laser probe beam was used, and PA and PBD spectra of each sample were recorded at 8 cm−1 resolution at each of the four different interferometer scan velocities. Although the overall aspects of FT-IR/PA and FT-IR/PBD spectra are the same, the signal-to-noise ratios of PA spectra are appreciably better than those of PBD spectra because PBD detection is more prone to disturbance by vibration than is PA detection. Absorption bands appear at the same wavenumbers in PA and PBD spectra. However, the relative intensities of bands of PBD spectra depend on the absorptive properties of the powdered solids; with weak absorbers, some bands may not be detected at all. PAS can be used with all powders. PBDS is of little or no use for the examination of weakly absorbing powders unless they scatter IR radiation extensively.

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