Confocal Raman mapping

1992 ◽  
Vol 50 (2) ◽  
pp. 1514-1515
Author(s):  
J. Barbillat ◽  
M. Delhaye ◽  
P. Dhamelincourt
Keyword(s):  
Chemical Species ◽  
Diffraction Limit ◽  
Microscopic Level ◽  
Raman Mapping ◽  
Complete Spectrum ◽  
Laser Illumination ◽  
Ccd Detector ◽  
Raman Microprobe ◽  
Photodiode Array ◽  
Raman Image

Raman mapping, with a spatial resolution close to the diffraction limit, can help to reveal the distribution of chemical species at the surface of an heterogeneous sample.As early as 1975,three methods of sample laser illumination and detector configuration have been proposed to perform Raman mapping at the microscopic level (Fig. 1),:- Point illumination:The basic design of the instrument is a classical Raman microprobe equipped with a PM tube or either a linear photodiode array or a two-dimensional CCD detector. A laser beam is focused on a very small area ,close to the diffraction limit.In order to explore the whole surface of the sample,the specimen is moved sequentially beneath the microscope by means of a motorized XY stage. For each point analyzed, a complete spectrum is obtained from which spectral information of interest is extracted for Raman image reconstruction.- Line illuminationA narrow laser line is focused onto the sample either by a cylindrical lens or by a scanning device and is optically conjugated with the entrance slit of the stigmatic spectrograph.

scholarly journals From Far-Field to Near-Field Micro- and Nanoparticle Optical Trapping

2020 ◽  
Vol 10 (4) ◽  
pp. 1375 ◽  
Author(s):  
Theodoros D. Bouloumis ◽  
Síle Nic Chormaic
Keyword(s):  
Optical Tweezers ◽  
Near Field ◽  
Metallic Nanostructures ◽  
Diffraction Limit ◽  
Submicron Particles ◽  
Great Success ◽  
Laser Illumination ◽  
Minimum Particle Size ◽  
Standard Tool ◽  
Established Technique

Optical tweezers are a very well-established technique that have developed into a standard tool for trapping and manipulating micron and submicron particles with great success in the last decades. Although the nature of light enforces restrictions on the minimum particle size that can be efficiently trapped due to Abbe’s diffraction limit, scientists have managed to overcome this problem by engineering new devices that exploit near-field effects. Nowadays, metallic nanostructures can be fabricated which, under laser illumination, produce a secondary plasmonic field that does not suffer from the diffraction limit. This advance offers a great improvement in nanoparticle trapping, as it relaxes the trapping requirements compared to conventional optical tweezers although problems may arise due to thermal heating of the metallic nanostructures. This could hinder efficient trapping and damage the trapped object. In this work, we review the fundamentals of conventional optical tweezers, the so-called plasmonic tweezers, and related phenomena. Starting from the conception of the idea by Arthur Ashkin until recent improvements and applications, we present the principles of these techniques along with their limitations. Emphasis in this review is on the successive improvements of the techniques and the innovative aspects that have been devised to overcome some of the main challenges.

Raman Microprobe Analysis of Laser-Induced Microstructures

1985 ◽  
Vol 51 ◽  
Author(s):  
P. M. Fauchet
Keyword(s):  
Spatial Resolution ◽  
Microprobe Analysis ◽  
Pulsed Laser ◽  
Amorphous Films ◽  
Periodic Surface ◽  
Laser Illumination ◽  
Explosive Crystallization ◽  
Raman Microprobe ◽  
Similarities And Differences

ABSTRACTWe study the composition, stress and structure variations across periodic surface undulations produced by pulsed laser illumination of semiconductors, by explosive crystallization of amorphous films, and by laser-assisted CVD. These variations are mapped out with a one micron spatial resolution using a Raman microprobe. Similarities and differences between the three cases are pointed out. These results are also compared to those obtained by deliberately exposing the sample to interfering beams.

scholarly journals In situ Raman mapping of art objects

2016 ◽  
Vol 374 (2082) ◽  
pp. 20160039 ◽  
Author(s):  
D. Lauwers ◽  
Ph. Brondeel ◽  
L. Moens ◽  
P. Vandenabeele
Keyword(s):  
Raman Spectroscopy ◽  
Spatial Distribution ◽  
Chemical Information ◽  
Raman Mapping ◽  
In Situ Raman ◽  
Art Objects ◽  
Mapping System ◽  
Non Destructive ◽  
Raman Image

Raman spectroscopy has grown to be one of the techniques of interest for the investigation of art objects. The approach has several advantageous properties, and the non-destructive character of the technique allowed it to be used for in situ investigations. However, compared with laboratory approaches, it would be useful to take advantage of the small spectral footprint of the technique, and use Raman spectroscopy to study the spatial distribution of different compounds. In this work, an in situ Raman mapping system is developed to be able to relate chemical information with its spatial distribution. Challenges for the development are discussed, including the need for stable positioning and proper data treatment. To avoid focusing problems, nineteenth century porcelain cards are used to test the system. This work focuses mainly on the post-processing of the large dataset which consists of four steps: (i) importing the data into the software; (ii) visualization of the dataset; (iii) extraction of the variables; and (iv) creation of a Raman image. It is shown that despite the challenging task of the development of the full in situ Raman mapping system, the first steps are very promising. This article is part of the themed issue ‘Raman spectroscopy in art and archaeology’.

A high-throughput confocal Raman microprobe based on a single grating spectrograph and CCD detector

1992 ◽  
Vol 50 (2) ◽  
pp. 1506-1507
Author(s):  
Fran Adar
Keyword(s):  
Focal Length ◽  
Low Frequency ◽  
Notch Filter ◽  
Excitation Wavelength ◽  
Limiting Factor ◽  
Trade Off ◽  
Practical Usefulness ◽  
Ccd Detector ◽  
Raman Microprobe ◽  
Confocal Raman

The availability of sharp cut-on holographic notch filters has enabled the design of simplified, compact Raman instruments for many applications where the size, complexity, and/or cost of instrumentation has been a significant limiting factor. With such a filter, a confocal Raman microprobe has been constructed around a 0.5 m focal length monochromator and 1” CCD detector. This system provides all the microprobe capabilities of the larger systems, including full confocal aperturing with spatial resolution determined by diffraction limitations. Since the gratings are kinematically mounted and easily interchangeable, the choice of grating will determine the trade-off on the array between spectral coverage and spectral resolution for any excitation wavelength between 400 and 830 nm.The practical usefulness of the system as a confocal Raman microprobe will be determined by the low frequency cut-off and the acquisition times. The low frequency cut-off will depend on the notch filter; at laser wavelengths shorter than 550nm the cut-off today is about 100-200 cm-1.

Raman Image Measurements of Laser-Recrystallized Polycrystalline Si Films by a Scanning Raman Microprobe

1986 ◽  
Vol 25 (Part 2, No. 3) ◽  
pp. L222-L224 ◽  
Author(s):  
Shin-ichi Nakashima ◽  
Kohji Mizoguchi ◽  
Yasuo Inoue ◽  
Michihiro Miyauchi ◽  
Akiyoshi Mitsuishi ◽  
...  
Keyword(s):  
Raman Microprobe ◽  
Si Films ◽  
Raman Image

Rapid Analysis of Raman Image Data Using Two-Way Multivariate Curve Resolution

1998 ◽  
Vol 52 (6) ◽  
pp. 797-807 ◽  
Author(s):  
Jeremy J. Andrew ◽  
Thomas M. Hancewicz
Keyword(s):  
Orthogonal Projection ◽  
Chemical Species ◽  
Image Data ◽  
Rapid Analysis ◽  
Principal Factor ◽  
Multivariate Curve Resolution ◽  
Curve Resolution ◽  
Current Curve ◽  
Image Noise Reduction ◽  
Raman Image

The application of standard two-way curve resolution methods is reported for analysis of three-way Raman image data. Two current curve resolution methods are described: principal factor multivariate curve resolution (PF-MCR), which uses principal factor analysis (PFA) combined with varimax rotation and alternating least-squares optimization (ALS), and orthogonal projection multivariate curve resolution (OP-MCR), which uses a Gram–Schmidt modified orthogonal projection approach (OPA) followed by ALS. The OP-MCR technique is shown to be an extremely rapid method of analysis producing results equivalent to those of PF-MCR in one-third to one-fourth the time. The results from MCR analysis using either method provide the number of chemical species present in the sample, the spectrum of each species for identification, and the concentration image for each species. The additional benefit of image noise reduction also results from the MCR techniques. A brief description of the theory is presented followed by analysis and comparison of results for two real Raman image data. A discussion is given addressing the rapid analysis aspects of OP-MCR and the relative merits and drawbacks of the technique in comparison to PF-MCR. The use of data subsampling is also discussed as a way of decreasing analysis time without loss in accuracy or performance.

Analysis of electron-diffraction intensity profiles using a photodiode-array detection system

1983 ◽  
Vol 41 ◽  
pp. 322-323
Author(s):  
J. B. Warren
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Detection System ◽  
High Energy ◽  
Photographic Emulsion ◽  
Diffraction Intensity ◽  
Silicon Photodiode ◽  
Photodiode Array Detection ◽  
Analog To Digital ◽  
Photodiode Array

Electron diffraction intensity profiles have been used extensively in studies of polycrystalline and amorphous thin films. In previous work, diffraction intensity profiles were quantitized either by mechanically scanning the photographic emulsion with a densitometer or by using deflection coils to scan the diffraction pattern over a stationary detector. Such methods tend to be slow, and the intensities must still be converted from analog to digital form for quantitative analysis. The Instrumentation Division at Brookhaven has designed and constructed a electron diffractometer, based on a silicon photodiode array, that overcomes these disadvantages. The instrument is compact (Fig. 1), can be used with any unmodified electron microscope, and acquires the data in a form immediately accessible by microcomputer.Major components include a RETICON 1024 element photodiode array for the de tector, an Analog Devices MAS-1202 analog digital converter and a Digital Equipment LSI 11/2 microcomputer. The photodiode array cannot detect high energy electrons without damage so an f/1.4 lens is used to focus the phosphor screen image of the diffraction pattern on to the photodiode array.

A simplified method of emulsion coating and development for quantitative electron microscopic radioautography

1978 ◽  
Vol 36 (2) ◽  
pp. 64-65
Author(s):  
K. Yoshida ◽  
F. Murata ◽  
S. Ohno ◽  
T. Nagata
Keyword(s):  
Mass Production ◽  
Identical Condition ◽  
Microscopic Level ◽  
Electron Microscopic Level ◽  
Electron Microscopic ◽  
Simplified Method ◽  
Complicated Process ◽  
Critical Problems ◽  
Electron Microscopic Radioautography ◽  
Quantitative Radioautography

IntroductionSeveral methods of mounting emulsion for radioautography at the electron microscopic level have been reported. From the viewpoint of quantitative radioautography, however, there are many critical problems in the procedure to produce radioautographs. For example, it is necessary to apply and develop emulsions in several experimental groups under an identical condition. Moreover, it is necessary to treat a lot of grids at the same time in the dark room for statistical analysis. Since the complicated process and technical difficulties in these procedures are inadequate to conduct a quantitative analysis of many radioautographs at once, many factors may bring about unexpected results. In order to improve these complicated procedures, a simplified dropping method for mass production of radioautographs under an identical condition was previously reported. However, this procedure was not completely satisfactory from the viewpoint of emulsion homogeneity. This paper reports another improved procedure employing wire loops.

Ultrastructural Investigation of Spontaneous Pituitary Adenomas in Aging Sprague-Dawley Rats

1982 ◽  
Vol 40 ◽  
pp. 216-217
Author(s):  
D. J. McComb ◽  
J. Beri ◽  
F. Zak ◽  
K. Kovacs
Keyword(s):  
Microscopic Study ◽  
Pituitary Adenomas ◽  
Wistar Rats ◽  
Microscopic Level ◽  
Sprague Dawley ◽  
Prolactin Cells ◽  
Light Microscopic Level ◽  
Ultrastructural Investigation ◽  
Sprague Dawley Rats ◽  
Long Evans

Investigation of the spontaneous pituitary adenomas in rat have been limited mainly to light microscopic study. Furth et al. (1973) described them as chromophobic, secreting prolactin. Kovacs et al. (1977) in an ul trastructural investigation of adenomas of old female Long-Evans rats, found that they were composed of prolactin cells. Berkvens et al. (1980) using immunocytochemistry at the light microscopic level, demonstrated that some spontaneous tumors of old Wistar rats could contain GH, TSH or ACTH as well as PRL.

Chemical Species Identification in an SEM by Changes in Emitted X-Ray Energies

1974 ◽  
Vol 32 ◽  
pp. 570-571
Author(s):  
R. H. Duff
Keyword(s):  
Species Identification ◽  
Valence Electron ◽  
Chemical Species ◽  
X Rays ◽  
Chemical Bonds ◽  
Small Shift ◽  
X Ray ◽  
Electron Transitions ◽  
Peak Energy ◽  
Chemical Combination

A material irradiated with electrons emits x-rays having energies characteristic of the elements present. Chemical combination between elements results in a small shift of the peak energies of these characteristic x-rays because chemical bonds between different elements have different energies. The energy differences of the characteristic x-rays resulting from valence electron transitions can be used to identify the chemical species present and to obtain information about the chemical bond itself. Although these peak-energy shifts have been well known for a number of years, their use for chemical-species identification in small volumes of material was not realized until the development of the electron microprobe.

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