Thermal Diffusion Length

2016 ◽  
Author(s):  
Masahide Terazima ◽  
Noboru Hirota ◽  
Silvia E. Braslavsky ◽  
Andreas Mandelis ◽  
Stephen E. Bialkowski ◽  
...  
Keyword(s):  
Thermal Diffusion ◽  
Diffusion Length ◽  
Thermal Diffusion Length

Advantages of Phase Analysis in Fourier Transform Infrared Photoacoustic Spectroscopy

1988 ◽  
Vol 42 (1) ◽  
pp. 134-138 ◽  
Author(s):  
Lionel Bertrand
Keyword(s):  
Fourier Transform ◽  
Phase Analysis ◽  
Thermal Diffusion ◽  
Photoacoustic Spectroscopy ◽  
Diffusion Length ◽  
Fourier Transform Infrared ◽  
Photoacoustic Signal ◽  
Thermal Diffusion Length ◽  
Phase Saturation ◽  
Infrared Photoacoustic Spectroscopy

Fourier transform infrared photoacoustic spectroscopy is greatly improved by the simultaneous measurement of the photoacoustic signal amplitude and phase. Saturation effects, sample dilation, and optical scattering, even in heterogeneous samples, can be easily corrected to give the absorption coefficient real value. Quantitative analyses without any special sample preparation or special photoacoustic cell are now possible. Moreover, the phase of the photoacoustic signal permits depth localization of the absorbing species within the thermal diffusion length. Surface analyses are thus possible that have a depth resolution at least one order of magnitude higher than that obtained by changing the thermal diffusion length. In this paper we illustrate the advantages of phase analysis in Fourier transform infrared photoacoustic spectroscopy with the detection of sorbed water in polyethylene.

scholarly journals Measurement of Contrast and Spatial Resolution for the Photothermal Imaging Method

2019 ◽  
Vol 9 (10) ◽  
pp. 1996 ◽  
Author(s):  
Moojoong Kim ◽  
Jaisuk Yoo ◽  
Dong-Kwon Kim ◽  
Hyunjung Kim
Keyword(s):  
Thermal Diffusion ◽  
Spatial Resolution ◽  
Diffusion Length ◽  
Beam Radius ◽  
Imaging Method ◽  
Modulation Transfer ◽  
Thermal Diffusion Length ◽  
Line Spread Function ◽  
Photothermal Imaging

Analyzing the quality of images generated from an imaging method is essential for determining the limits and applicability of that method. This study analyzed the quality of images resulting from a photothermal imaging method by applying the line spread function and the modulation transfer function to the spatial resolution and contrast, on the basis of certain parameters of the photothermal imaging method for a copper-resin double-layered structure. The parameters are the ratio of the first-layer thickness to the thermal diffusion length ( L f / L d ) and the ratio of the pump-beam radius to the thermal diffusion length ( R b / L d ). The phase delay profile (edge response function, ERF) of the subsurface structure derived from the photothermal imaging method becomes dimensionless upon division by the thermal diffusion length; as the ratio L f / L d increases, the spatial resolution and contrast increase.

The Thermal Diffusion Length Problem in an Array of Plates

2004 ◽  
Vol 148 (3) ◽  
pp. 453-457 ◽  
Author(s):  
J. S. Cassell ◽  
M. M. R. Williams
Keyword(s):  
Thermal Diffusion ◽  
Diffusion Length ◽  
Thermal Diffusion Length

scholarly journals Study on Ablation Characteristics of Femyosecond Laser Nanoscale Processing for Aluminum Nitride and LeadZirconate Titanate Ceramics

2021 ◽  
Author(s):  
C. Y. Ho ◽  
Liangliang Zhou ◽  
Chang-Wei Xiong ◽  
Dongkai Qiao
Keyword(s):  
Aluminum Nitride ◽  
Thermal Diffusion ◽  
Lead Zirconate Titanate ◽  
Diffusion Length ◽  
Pulsed Laser ◽  
Lead Zirconate ◽  
Pzt Ceramics ◽  
Optical Penetration Depth ◽  
Laser Fluences ◽  
Ultrashort Pulsed Laser

Abstract This paper analytically investigates an ultrashort pulsed laser nanoscale processing for aluminum nitride (AIN) and lead zirconate titanate (PZT) ceramics. Processing characteristics of an ultra-short pulsed laser is different from that of long-pulsed laser due to ultrahigh intensity, ultrahigh power, and ultrashort time. The ultrasmall processing for materials can achieved by an ultra-short pulsed laser. This study proposes a model to analyze an ultrashort pulsed laser nanoscale processing for aluminum nitride (AIN) and lead zirconate titanate (PZT) ceramics. The effects of optical penetration absorption and thermal diffusion on temperature are also discussed. The results reveal that the variation of ablation rate with laser fluences predicted by this work agrees with the available measured data for an ultrashort pulsed laser processing for AIN and PZT. For femtosecond lasers, the optical absorption and thermal diffusion, respectively, governs the ablated depth per pulse at the low and high laser fluences. The thermal diffusion length is small relative to the optical penetration depth for femtosecond laser. The optical penetration absorption governs the temperature in the workpiece. On the other hand, for the picosecond laser, the thermal diffusion length is large compared to the optical penetration depth. The thermal diffusion determines the temperature in the workpiece.

Quantitative Analysis of Kaolinite/Silica and Kaolinite/KBr Mixtures by Photoacoustic FT-IR Spectroscopy

1994 ◽  
Vol 48 (7) ◽  
pp. 871-874 ◽  
Author(s):  
A. M. Saffa ◽  
K. H. Michaelian
Keyword(s):  
Infrared Spectroscopy ◽  
Quantitative Analysis ◽  
Ir Spectroscopy ◽  
Absorption Coefficient ◽  
Linear Relationship ◽  
Thermal Diffusion ◽  
Diffusion Length ◽  
Average Error ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Photoacoustic FT-IR spectroscopy was used to quantify kaolinite in binary mixtures with KBr and silica, with the use of a linear relationship between the reciprocals of photoacoustic intensity and kaolinite concentration. The method is valid for both dilute and concentrated mixtures; an average error of 12% was obtained for kaolinite concentrations ranging from 15 to 80%. The technique thus compares favorably with more common approaches that require low analyte concentrations. It is concluded that quantitative photoacoustic infrared spectroscopy is feasible provided that the magnitude of the product of thermal diffusion length and absorption coefficient is taken into account.

scholarly journals Генерация фотоакустического сигнала двухслойными прозрачными образцами с поглощающей подложкой

2019 ◽  
Vol 45 (9) ◽  
pp. 30
Author(s):  
Т.Х. Салихов ◽  
Н. Меликхуджа ◽  
А. Махмалатиф
Keyword(s):  
Frequency Dependence ◽  
Free Path ◽  
Thermal Diffusion ◽  
Diffusion Length ◽  
Signal Amplitude ◽  
Photoacoustic Signal ◽  
Buffer Gas ◽  
Photoacoustic Cell ◽  
Opposite Case ◽  
Absorbing Substrate

AbstractA theory of generation of a photoacoustic signal in a two-layer transparent sample on an absorbing substrate to a buffer gas of a photoacoustic cell has been developed. We have shown that the frequency dependence of the photoacoustic signal amplitude excited in the absorbing substrate obeys the law ∝ ω^–1, when a free path of photons is less than the thermal diffusion length, and is proportional to ω^–3/2 in the opposite case.

Surface recombination effects on minority carrier diffusion length measurements using electron beam-induced current

1990 ◽  
Vol 48 (4) ◽  
pp. 744-745
Author(s):  
D.P. Malta ◽  
M.L. Timmons
Keyword(s):  
Electron Beam ◽  
Beam Energy ◽  
Minority Carrier ◽  
Diffusion Length ◽  
Effective Diffusion ◽  
Surface Recombination ◽  
Surface Recombination Velocity ◽  
Logarithmic Scale ◽  
Minority Carrier Diffusion Length ◽  
Carrier Diffusion

Measurement of the minority carrier diffusion length (L) can be performed by measurement of the rate of decay of excess minority carriers with the distance (x) of an electron beam excitation source from a p-n junction or Schottky barrier junction perpendicular to the surface in an SEM. In an ideal case, the decay is exponential according to the equation, I = Ioexp(−x/L), where I is the current measured at x and Io is the maximum current measured at x=0. L can be obtained from the slope of the straight line when plotted on a semi-logarithmic scale. In reality, carriers recombine not only in the bulk but at the surface as well. The result is a non-exponential decay or a sublinear semi-logarithmic plot. The effective diffusion length (Leff) measured is shorter than the actual value. Some improvement in accuracy can be obtained by increasing the beam-energy, thereby increasing the penetration depth and reducing the percentage of carriers reaching the surface. For materials known to have a high surface recombination velocity s (cm/sec) such as GaAs and its alloys, increasing the beam energy is insufficient. Furthermore, one may find an upper limit on beam energy as the diameter of the signal generation volume approaches the device dimensions.

Thermal diffusion in hydrogen-helium mixtures

1963 ◽  
Vol 60 ◽  
pp. 172-177 ◽  
Author(s):  
C. J. G. Slieker ◽  
A. E. de Vries
Keyword(s):  
Thermal Diffusion ◽  
Helium Mixtures
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