Determination of thermal and optical properties of ion implanted polyetheretherketone films by photothermal spectroscopies

Abstract

A composite photothermal technique for the measurement of thermal properties of solids J. Appl. Phys. 104, 066101 (2008) Photothermal spectroscopies, photopyroelectric spectroscopy and photoacoustic spectroscopy ͑PAS͒, were used to study the thermal and optical properties of untreated and N + ion implanted polyetheretherketone ͑PEEK͒ films. The photopyroelectric ͑PPE͒ intensity signal and its phase were independently measured as a function of wavelength and chopping frequency in the saturation part of the PPE spectrum. Equations for both the intensity and the phase of the PPE signal were used to fit the experimental results. From these fits we obtained the thermal diffusivity coefficient, the thermal conductivity, and the specific heat of the samples, as well as a value for the condensed phase optical gap. Additionally, using PAS we carried out a quantitative depth profile analysis of the optical properties of the ion implanted PEEK films. Since the thermal diffusion length varies inversely with the square root of chopping modulation frequency, at high chopping frequencies surface information is obtained. At low chopping frequencies information concerning the properties of the bulk is obtained. The overall objectives of this study are to understand and quantify how ion implantation affects the thermal and optical properties of the polymer, particularly within the implant region. We find that significant changes do occur, and our results have implications for the use of ion implantation to create plastic electronic and sensor devices.

Photoacoustic spectroscopy as an approach to assess chemical modifications in edible oils

“…The gas acts as a piston in order to produce a sound wave which is detected by a microphone connected to the chamber. [6][7][8][9][10] As the microphone signal is proportional to radiation absorption by the sample, PAS gives results similar to absorbance spectra, i.e., conventional optical absorption spectroscopy. Also, as the signal depends on the modulation of the radiation source, PAS is able to perform a depth profile of the absorption in the sample, that is, at high modulation frequencies absorption information about the sample near the surface is obtained, while at low modulation frequencies the data come from deeper within the sample.…”

“…5 The heat propagation across the whole chamber is governed by heat diffusion equations of each medium coupled via boundary conditions at the interfaces (T a = T b and k a dT a /dx = k b dT b /dx, a and b are adjacent media, T is temperature and k is thermal conductivity). After all mathematical treatment, the normalized photoacoustic signal (S n ) produced by the microphone is: [5][6][7][8][9][10]17 (2) where r s = b s /s s , b s is the sample optical absorption coefficient, s s = (1 + i)a s with i = (-1) ½ and a s = (p f /a s ) ½ , a s is the sample thermal diffusivity, b nm = k n a n /k m a m (n = g, s, b, that is, g = gas, s = sample, b = backing), and L S is the sample thickness. This equation is a complex mathematical function of the optical, thermal and geometrical parameters of the system, and it governs our results for all the chopper frequencies.…”

Thermophysical property of undercooled liquid binary alloy composed of metallic and semiconductor elements

“…The thermophysical properties of undercooled liquid alloys are of great significance both for understanding liquid characteristics and for controlling crystal growth processes [1][2][3][4][5][6][7][8][9][10][11]. Therefore, research on this aspect has attracted considerable attention in the last ten years [3][4][5][6][7][8][9][10][11][12][13][14][15]. These thermophysical properties include density, excess volume, enthalpy, mixing enthalpy and specific heat, etc.…”

“…So far, two 1 Author to whom any correspondence should be addressed. main methods have been used to obtain these thermophysical properties: one is experimental measurement [5][6][7][8][9][10][11], such as levitation calorimetry which is applied for specific heat measurement and recording shadow of the levitated droplet for determining density. The other is computer simulation [12][13][14][15][16][17][18][19].…”

“…Up to now, although there have been some reports [5][6][7][8][9][10][11], the thermophysical properties data for undercooled metals and alloys are still very limited, especially for high melting-temperature alloys. In the available literature, most experimental and simulated research on thermophysical properties focused on pure elements and those alloys were composed of only metallic elements.…”