Diffraction-free acoustic detection for optoacoustic depth profiling of tissue using an optically transparent polyvinylidene fluoride pressure transducer operated in backward and forward mode

2005 ◽  
Vol 10 (2) ◽  
pp. 024035 ◽  
Author(s):  
Michael Jaeger ◽  
Joël J. Niederhauser ◽  
Marjaneh Hejazi ◽  
Martin Frenz
Keyword(s):  
Polyvinylidene Fluoride ◽  
Pressure Transducer ◽  
Depth Profiling ◽  
Acoustic Detection ◽  
Optically Transparent

Depth Profiling in Diffusely Scattering Media Using Raman Spectroscopy and Picosecond Kerr Gating

2005 ◽  
Vol 59 (2) ◽  
pp. 200-205 ◽  
Author(s):  
P. Matousek ◽  
N. Everall ◽  
M. Towrie ◽  
A. W. Parker
Keyword(s):  
Depth Profiling ◽  
Depth Resolution ◽  
Disease Diagnosis ◽  
Excitation Wavelength ◽  
Raman Signal ◽  
Scattering Media ◽  
Pmma Layer ◽  
Photon Propagation ◽  
Laser Raman ◽  
Optically Transparent

We demonstrate how pulsed laser Raman excitation (∼1 ps) followed by fast optical Kerr gating (∼4 ps) can be used to effectively separate Raman signals originating from different depths in heterogeneous diffusely scattering media. The diffuse scattering slows down photon propagation through turbid samples enabling higher depth resolution than would be obtained for a given instrumental time resolution in an optically transparent medium. Two types of experiments on two-layer systems demonstrate the ability to differentiate between surface and sub-surface Raman signals. A Raman spectrum was obtained of stilbene powder buried beneath a 1 mm over-layer of PMMA (poly(methyl methacrylate)) powder. The signal contrasts of the lower stilbene layer and upper PMMA layer were improved by factors ≥5 and ≥180, respectively, by rejecting the Raman component of the counterpart layer. The ability to select the Raman signal of a thin top surface layer in preference to those from an underlying diffusely scattering substrate was demonstrated using a 100 μm thick optically transparent film of PET (poly(ethylene terephthalate)) on top of stilbene powder. The gating resulted in the suppression of the underlying stilbene Raman signal by a factor of 1200. The experiments were performed in back-scattering geometry using 400 nm excitation wavelength. The experimental technique should be well suited to biomedical applications such as disease diagnosis.

Depth Profiling of Hydrogen in Ion-Implanted Polymers

1983 ◽  
Vol 27 ◽  
Author(s):  
J. David Carlson ◽  
Peter P. Pronko ◽  
David C. Ingram
Keyword(s):  
Cross Sections ◽  
Polyvinylidene Fluoride ◽  
Depth Profiling ◽  
Polymeric Materials ◽  
Reaction Cross ◽  
High Mass ◽  
Hydrogen Distribution ◽  
Nickel Ions ◽  
Proton Recoil ◽  
Ion Implanted

ABSTRACTDepth profiling of hydrogen in polymeric materials poses special problems. Backscattering methods are ruled out because of kinematics. Nuclear reaction methods are undesirable because small reaction cross sections necessitate large fluences of high mass projectiles and result in unacceptable levels of radiation damage. We have used a helium-induced proton-recoil technique with 3 MeV 4He particles to measure the hydrogen distribution in pristine and ion-implanted polyvinylidene fluoride (PVDF) films. The incident 4He particles stopped in the 25 micron PVDF films while the recoiling protons were detected after passing through the polymer film. Large changes in the hydrogen content of PVDF films implanted with modest fluences of 6 MeV carbon, oxygen and nickel ions were observed.

Depth-Profiling Studies of Double-Layer PVF2-on-PET Films by Fourier Transform Infrared Photoacoustic Spectroscopy

1986 ◽  
Vol 40 (7) ◽  
pp. 994-998 ◽  
Author(s):  
Marek W. Urban ◽  
Jack L. Koenig
Keyword(s):  
Fourier Transform ◽  
Michelson Interferometer ◽  
Depth Profiling ◽  
Fourier Transform Infrared ◽  
Poly Ethylene Terephthalate ◽  
Optically Transparent ◽  
Theoretical Predictions ◽  
Ft Ir ◽  
Poly Ethylene ◽  
Pet Film

Photoacoustic Fourier transform infrared spectroscopy (PA/FT-IR) is used to study films of poly(vinylidine fluoride) (PVF2) and poly(ethylene terephthalate) (PET). It is shown that PVF2 films over PET change the thermal diffusion length such that the sample PVF2-on-PET becomes optically transparent and thermally thick. By changing the mirror velocity of the Michelson interferometer it is possible to obtain spectra at various sample depths. The intensity of the carbonyl band of the lower PET film changes as a function of the mirror velocity. The log-log plot of these quantities gives a slope of −3/2, which agrees with theoretical predictions for thermally thick and optically transparent samples.

Dislocations, Ordering and Antiferromagnetic Domains in MnO

1970 ◽  
Vol 28 ◽  
pp. 522-523
Author(s):  
D. J. Barber ◽  
R. G. Evans
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Optical Microscopy ◽  
Defect Chemistry ◽  
Magnetic Structures ◽  
Optically Transparent ◽  
Magnetic Features ◽  
Antiferromagnetic Domains

Manganese (II) oxide, MnO, in common with CoO, NiO and FeO, possesses the NaCl structure and shows antiferromagnetism below its Neel point, Tn∼ 122 K. However, the defect chemistry of the four oxides is different and the magnetic structures are not identical. The non-stoichiometry in MnO2 small (∼2%) and below the Tn the spins lie in (111) planes. Previous work reported observations of magnetic features in CoO and NiO. The aim of our work was to find explanations for certain resonance results on antiferromagnetic MnO.Foils of single crystal MnO were prepared from shaped discs by dissolution in a mixture of HCl and HNO3. Optical microscopy revealed that the etch-pitted foils contained cruciform-shaped precipitates, often thick and proud of the surface but red-colored when optically transparent (MnO is green). Electron diffraction and probe microanalysis indicated that the precipitates were Mn2O3, in contrast with recent findings of Co3O4 in CoO.

Preferential Sputtering of Ni3Al Single Crystals Studied Using Atom-Probe Field-Ion Microscopy and XPS

1981 ◽  
Vol 39 ◽  
pp. 16-17
Author(s):  
M.P. Thomas ◽  
A.R. Waugh ◽  
M.J. Southon ◽  
Brian Ralph
Keyword(s):  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Atom Probe ◽  
Probe Field ◽  
Preferential Sputtering ◽  
Argon Ion Bombardment ◽  
Argon Ion

It is well known that ion-induced sputtering from numerous multicomponent targets results in marked changes in surface composition (1). Preferential removal of one component results in surface enrichment in the less easily removed species. In this investigation, a time-of-flight atom-probe field-ion microscope A.P. together with X-ray photoelectron spectroscopy XPS have been used to monitor alterations in surface composition of Ni3Al single crystals under argon ion bombardment. The A.P. has been chosen for this investigation because of its ability using field evaporation to depth profile through a sputtered surface without the need for further ion sputtering. Incident ion energy and ion dose have been selected to reflect conditions widely used in surface analytical techniques for cleaning and depth-profiling of samples, typically 3keV and 1018 - 1020 ion m-2.

Atomic force microscopy (AFM) of the topography of silicon surfaces exposed to ion beams

1992 ◽  
Vol 50 (2) ◽  
pp. 1132-1133
Author(s):  
Mark Denker ◽  
Jennifer Wall ◽  
Mark Ray ◽  
Richard Linton
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Incidence Angle ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Ion Beams ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Trace Impurities ◽  
Energy Dose

Reactive ion beams such as O2+ and Cs+ are used in Secondary Ion Mass Spectrometry (SIMS) to analyze solids for trace impurities. Primary beam properties such as energy, dose, and incidence angle can be systematically varied to optimize depth resolution versus sensitivity tradeoffs for a given SIMS depth profiling application. However, it is generally observed that the sputtering process causes surface roughening, typically represented by nanometer-sized features such as cones, pits, pyramids, and ripples. A roughened surface will degrade the depth resolution of the SIMS data. The purpose of this study is to examine the relationship of the roughness of the surface to the primary ion beam energy, dose, and incidence angle. AFM offers the ability to quantitatively probe this surface roughness. For the initial investigations, the sample chosen was <100> silicon, and the ion beam was O2+.Work to date by other researchers typically employed Scanning Tunneling Microscopy (STM) to probe the surface topography.

Influence of magnetic field to the allocation of imputiry molecules in the structure of optically transparent polymer films

2016 ◽  
Vol 38 (3) ◽  
pp. 205-210
Author(s):  
L.A. Bulavin ◽  
◽  
Yu.F. Zabashta ◽  
О.О. Brovko ◽  
L.Yu. Vergun ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Polymer Films ◽  
Optically Transparent
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