Optical Depth Profiling of Thin Films by Impulse Mirage Effect Spectroscopy. Part I: Theory

1994 ◽  
Vol 48 (9) ◽  
pp. 1054-1075 ◽  
Author(s):  
M. A. Schweitzer ◽  
J. F. Power
Keyword(s):  
Probe Beam ◽  
Fluid Layer ◽  
Three Dimensional ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Beam Deflection ◽  
Theoretical Expression ◽  
Mirage Effect ◽  
Photothermal Deflection ◽  
Effect Method

Impulse mirage effect/photothermal deflection spectrometry may be used to detect depth-dependent optical absorption in materials, through the time dependence of the probe beam deflection signal occurring in response to sample irradiation with a short excitation pulse. In this work a theoretical expression was derived for the normal and transverse photothermal deflection signals which occur in a sample with homogeneous thermal properties but where optical absorptivity varies with depth from the surface. An analytical solution of moderate simplicity is obtained for several cases of experimental interest, with three-dimensional heat conduction effects included. The depth profile resolution obtained with the mirage effect method is critically dependent on the distance between the sample layer probed and the offset position of the probe beam in the fluid layer above the sample. Saturation conditions and conditions for obtaining optimal depth resolution of continuous and discrete optical profiles are examined in detail.

Mirage-effect measurement of thermal diffusivity. Part II: theory

1986 ◽  
Vol 64 (9) ◽  
pp. 1168-1171 ◽  
Author(s):  
P. K. Kuo ◽  
E. D. Sendler ◽  
L. D. Favro ◽  
R. L. Thomas
Keyword(s):  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Probe Beam ◽  
Three Dimensional ◽  
Sample Surface ◽  
Bulk Sample ◽  
Effect Measurement ◽  
Dimensional Theory ◽  
Mirage Effect ◽  
Effect Technique

A three-dimensional theory of a mirage-effect technique for measuring thermal diffusivity of solids is presented. A formula that incorporates sizes and separations of the heating and probe beams; the height of the probe beam above the sample surface; the thermal properties of the sample, the gas, and the backing; and the thickness of the sample is developed. The results are compared with experiments on a bulk sample and on thin slabs of various thicknesses.

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.

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

1986 ◽  
Vol 40 (5) ◽  
pp. 636-641 ◽  
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.

Photoacoustic FT-IR Spectroscopy of Natural Copper Patina

1995 ◽  
Vol 49 (10) ◽  
pp. 1516-1524 ◽  
Author(s):  
Alex O. Salnick ◽  
Werner Faubel
Keyword(s):  
Depth Distribution ◽  
Depth Profiling ◽  
Beam Deflection ◽  
City Hall ◽  
Spectral Bands ◽  
Special Sample Preparation ◽  
Ft Ir ◽  
Infrared Photoacoustic Spectroscopy ◽  
Ft Ir Spectroscopy

Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) has proved to be a useful tool for nondestructive testing of copper corrosion layer (patina) formed in the atmosphere. The samples cut from a piece of the roof of the Stockholm City Hall were examined without any additional pretreatment. The components of the patina—brochantite Cu4(OH)6SO4, antlerite Cu3(OH)4SO4, and basic cupric carbonate Cu2CO3(OH)6 · H2O—as well as some other minerals were identified. The photothermal beam deflection (PBD) method was used for independent photoacoustic characterization of the samples. The depth profiling capability of FT-IR/PAS was used to determine the degree of photoacoustic saturation of the spectral bands and to evaluate the depth distribution of the main patina components. The technique thus compares favorably with more common approaches of patina examination which are more expensive and require special sample preparation.

Investigation of Ge, As, and Au Diffusion in Non-Alloyed Epitaxial Au-Ge Ohmic Contacts to n-GaAs Using Secondary Ion Mass Spectroscopy Backside Sputter Depth-Profiling

1991 ◽  
Vol 240 ◽  
Author(s):  
H. S. LEE ◽  
R. T. Lareau ◽  
S. N. Schauer ◽  
R. P. Moerkirk ◽  
K. A. Jones ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Ion Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
High Concentration ◽  
Ohmic Behavior ◽  
Preferential Sputtering ◽  
Specific Contact ◽  
Secondary Ion ◽  
Diffusion Profiles

ABSTRACTA SIMS backside sputter depth-profile technique using marker layers is employed to characterize the diffusion profiles of the Ge, As, and Au in the Au-Ge contacts after annealing at 320 C for various times. This technique overcomes difficulties such as ion beam mixing and preferential sputtering and results in high depth resolution measurements since diffusion profiles are measured from low to high concentration. Localized reactions in the form of islands were observed across the surface of the contact after annealing and were composed of Au, Ge, and As, as determined by SIMS imaging and Auger depth profiling. Backside SIMS profiles indicate both Ge and Au diffusion into the GaAs substrate in the isalnd regions. Ohmic behavior was obtained after a 3 hour anneal with a the lowest average specific contact resistivity found to be ∼ 7 × 100−6 Ω- cm2.

Plane turbulent jets in a bounded fluid layer

1992 ◽  
Vol 241 ◽  
pp. 587-614 ◽  
Author(s):  
T. Dracos ◽  
M. Giger ◽  
G. H. Jirka
Keyword(s):  
Experimental Investigation ◽  
Cross Section ◽  
Fluid Layer ◽  
Three Dimensional ◽  
Turbulent Jets ◽  
Two Dimensional ◽  
Vortical Structures ◽  
Secondary Currents ◽  
Fluid Layers ◽  
Bounding Surfaces

An experimental investigation of plane turbulent jets in bounded fluid layers is presented. The development of the jet is regular up to a distance from the orifice of approximately twice the depth of the fluid layer. From there on to a distance of about ten times the depth, the flow is dominated by secondary currents. The velocity distribution over a cross-section of the jet becomes three-dimensional and the jet undergoes a constriction in the midplane and a widening near the bounding surfaces. Beyond a distance of approximately ten times the depth of the bounded fluid layer the secondary currents disappear and the jet starts to meander around its centreplane. Large vortical structures develop with axes perpendicular to the bounding surfaces of the fluid layer. With increasing distance the size of these structures increases by pairing. These features of the jet are associated with the development of quasi two-dimensional turbulence. It is shown that the secondary currents and the meandering do not significantly affect the spreading of the jet. The quasi-two-dimensional turbulence, however, developing in the meandering jet, significantly influences the mixing of entrained fluid.

A Probe Beam Deflection Study of Ion Exchange at Poly(vinylferrocene) Films in Aqueous and Nonaqueous Electrolytes

Langmuir ◽  
2002 ◽  
Vol 18 (7) ◽  
pp. 2756-2764 ◽  
Author(s):  
C. Barbero ◽  
M. C. Miras ◽  
E. J. Calvo ◽  
R. Kötz ◽  
O. Haas
Keyword(s):  
Ion Exchange ◽  
Probe Beam ◽  
Beam Deflection ◽  
Nonaqueous Electrolytes
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