1,721,004 research outputs found
Anisotropic Magnetocaloric Effect In Gadolinium Thin Films: Magnetization Measurements And Acoustic Detection
No full textIn this letter, it is demonstrated the ability of the magnetoacoustic technique in detecting the magnetocaloric effect in gadolinium thin films (1.0 μm and 3.0 μm thick), which is not accessible through conventional temperature sensors because of the reduced mass of the samples. The method, which detects the direct effect of the sample temperature variation, proved to be sensitive to the anisotropy of the films, making possible for the investigation of the anisotropic magnetocaloric effect. Magnetization measurements were also carried out, and from these measurements both the adiabatic temperature and the isothermal entropy variations were calculated. The acoustically detected magnetocaloric effect shows very good agreement with these calculations. © 2013 AIP Publishing LLC.11416Pecharsky, V.K., Gschneidner, Jr.K.A., (1999) J. Magn. Magn. Mater., 200, p. 44. , 10.1016/S0304-8853(99)00397-2Pecharsky, V.K., Gschneidner, Jr.K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 10.1103/PhysRevLett.78.4494Gadioli, G.Z., Rouxinol, F.P., Gelamo, R.V., Santos, A.O., Cardoso, L.P., Moraes, M.A.B., (2008) J. Appl. Phys., 103, p. 093916. , 10.1063/1.2838462Soffner, M.E., Guimarães, A.O., Da Silva, E.C., Mansanares, A.M., (2013) Appl. Phys. A, 112, pp. 403-409. , 10.1007/s00339-012-7414-4Guimarães, A.O., Soffner, M.E., Mansanares, A.M., Coelho, A.A., Carvalho, A.M.G., Pires, M.J.M., Gama, S., Da Silva, E.C., (2009) Phys. Rev. B, 80, p. 134406. , 10.1103/PhysRevB.80.134406Guimarães, A.O., Soffner, M.E., Mansanares, A.M., Coelho, A.A., Carvalho, A.M.G., Pires, M.J.M., Gama, S., Da Silva, E.C., (2010) J. Appl. Phys., 107, p. 073524. , 10.1063/1.3357375Soffner, M.E., Mansanares, A.M., Gandra, F.C.G., Coelho, A.A., Gama, S., Carvalho, A.M.G., Pires, M.J.M., Da Silva, E.C., (2010) J. Phys. D: Appl. Phys., 43, p. 445002. , 10.1088/0022-3727/43/44/445002Soffner, M.E., Tedesco, J.C.G., Pedrochi, F., Gadioli, G.Z., De Moraes, M.A.B., Guimarães, A.O., Da Silva, E.C., Mansanares, A.M., (2012) Thin Solid Films, 520, pp. 3634-3640. , 10.1016/j.tsf.2011.12.042Pecharsky, V.K., Gschneidner, Jr.K.A., (1999) J. Appl. Phys., 86, p. 565. , 10.1063/1.370767Glorieux, C., Thoen, J., Bednarz, G., White, M.A., Geldart, D.J.W., (1995) Phys. Rev. B, 52, p. 12770. , 10.1103/PhysRevB.52.12770Bahl, C.R.H., Nielsen, K.K., (2009) J. Appl. Phys., 105, p. 013916. , 10.1063/1.3056220Foldeaki, M., Chahine, R., Bose, T.K., (1995) J. Appl. Phys., 77 (7), p. 3528. , 10.1063/1.358648Miller, C.W., Williams, D.V., Bingham, N.S., Srikanth, H., (2010) J. Appl. Phys., 107, pp. 09A903. , 10.1063/1.3335515Kirby, B.J., Lau, J.W., Williams, D.V., Bauer, C.A., Miller, C.W., (2011) J. Appl. Phys., 109, p. 063905. , 10.1063/1.3555101Touloukian, Y.S., Powell, R.W., Ho, C.Y., Nicolaou, M.C., (1973) Thermophysical Properties of Matter: Thermal Diffusivity, , (IFI/Plenum, New York, Washington), Vol. 1
Angular Dependence Of The Photothermally Modulated Magnetic Resonance In Gd Thin Films
No full textIn this paper we use electron spin resonance and photothermally modulated magnetic resonance techniques to investigate gadolinium thin films as a function of the orientation of the film surface with respect to the external magnetic field and of the temperature, around the magnetic phase transition temperature. We observe that, in the ferromagnetic phase, the resonance line is shifted up to higher external magnetic fields when the angle between the film surface and the field increases, revealing the magnetic anisotropy of the sample. At the same time, when the temperature is augmented to values higher than the phase transition temperature, the external field of the resonance collapses back to the expected value in the paramagnetic phase for all orientations. We also demonstrated that, even for the perpendicular orientation (magnetic field perpendicular to the sample surface), the photothermally modulated magnetic resonance signal is maximized near the magnetic phase transition temperature. Furthermore, in the ferromagnetic phase the photothermally modulated magnetic resonance intensity is very sensitive to the orientation, showing a significant enhancement in the perpendicular direction. © 2012 Springer-Verlag Berlin Heidelberg.1122403409Orth, T., Netzelmann, U., Pelzl, J., (1988) Appl. Phys. Lett., 53, p. 1979. , 1988ApPhL.53.1979O 10.1063/1.100338Romano, J.A., Mansanares, A.M., Da Silva, E.C., Vargas, H., (1994) J. Phys., 4. , C7-667Meckenstock, R., Spodding, D., Pelzl, J., (2002) J. Magn. Mater., 240, p. 83. , 2002JMMM.240.83M 10.1016/S0304-8853(01)00754-5Poole, Jr.C.P., (1983) Electron Spin Resonance, , Wiley New YorkAbragam, A., Bleaney, B., (1986) Electron Paramagnetic Resonance of Transition Ions, , Dover New YorkSoffner, M.E., Tedesco, J.C.G., Mansanares, A.M., Gadioli, G.Z., Rouxinol, F.P., De Moraes, M.A.B., Da Silva, E.C., (2010) J. Phys. Conf. Ser., 214. , 012092 2010JPhCS.214a2092S 10.1088/1742-6596/214/1/012092Soffner, M.E., Tedesco, J.C.G., Pedrochi, F., Gadioli, G.Z., De Moraes, M.A.B., Guimarães, A.O., Da Silva, E.C., Mansanares, A.M., (2012) Thin Solid Films, 520, p. 3634. , 2012TSF.520.3634S 10.1016/j.tsf.2011.12.042Pecharsky, V.K., Gschneider, Jr.K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 1997PhRvL.78.4494P 10.1103/PhysRevLett.78.4494Foldeaki, M., Schnelle, W., Gmelin, E., Bernard, P., Koszegi, B., Giguere, A., Chahine, R., Bose, T.K., (1997) J. Appl. Phys., 82, p. 309. , 1997JAP.82.309F 10.1063/1.365813Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , Inst. Phys. Ser. Condens. Matter Phys. Institute of Physics Bristol 10.1887/0750309229Guimarães, A.O., Soffner, M.E., Mansanares, A.M., Coellho, A.A., Carvalho, A.M.G., Pires, M.J.M., Gama, S., Da Silva, E.C., (2009) Phys. Rev. B, 80. , 134406 2009PhRvB.80m4406G 10.1103/PhysRevB.80.134406Guimarães, A.O., Soffner, M.E., Mansanares, A.M., Coellho, A.A., Carvalho, A.M.G., Pires, M.J.M., Gama, S., Da Silva, E.C., (2010) J. Appl. Phys., 107. , 073524 2010JAP.107g3524G 10.1063/1.3357375Soffner, M.E., Mansanares, A.M., Gandra, F.C.G., Coelho, A.A., Gama, S., Carvalho, A.M.G., Pires, M.J.M., Da Silva, E.C., (2010) J. Phys. D, Appl. Phys., 43. , 445002 2010JPhD.43.5002S 10.1088/0022-3727/43/44/445002Gadioli, G.Z., Rouxinol, F.P., Gelamo, R.V., Dos Santos, A.O., Cardoso, L.P., De Moraes, M.A.B., (2008) J. Appl. Phys., 103. , 093916 2008JAP.103i3916G 10.1063/1.2838462Zakeri, Kh., Lindner, J., Barsukov, I., Meckenstock, R., Farle, M., Von Hörsten, U., Wende, H., Frait, Z., (2007) Phys. Rev. B, 76. , 104416 2007PhRvB.76j4416Z 10.1103/PhysRevB.76.104416Lindner, J., Barsukov, I., Raeder, C., Hassel, C., Posth, O., Meckenstock, R., Landeros, P., Mills, D.L., (2009) Phys. Rev. B, 80. , 224421 2009PhRvB.80v4421L 10.1103/PhysRevB.80.224421Rezende, S.M., Moura, J.A.S., De Aguiar, F.M., (1994) Phys. Rev. B, 49, p. 15105. , 1994PhRvB.4915105R 10.1103/PhysRevB.49.15105Landau, L.D., Lifshitz, E.M., (1935) Phys. Z. Sowjetunion, 8, p. 153. , 0012.28501Kittel, C., (1947) Phys. Rev., 71, p. 270. , 1947PhRv.71.270K 10.1103/PhysRev.71.270.2Kittel, C., (1948) Phys. Rev., 73, p. 155. , 1948PhRv.73.155K 10.1103/PhysRev.73.155Mansanares, A.M., Fournier, D., Boccara, A.C., (1993) Electron. Lett., 29 (23), p. 2045. , 10.1049/el:19931366Bernal-Alvarado, J., Mansanares, A.M., Da Silva, E.C., Moreira, S.G.C., (2003) Rev. Sci. Instrum., 74 (1), p. 697. , 2003RScI.74.697B 10.1063/1.1517726Glorieux, C., Thoen, J., Bednarz, G., White, M.A., Geldart, D.J.W., (1995) Phys. Rev. B, 52, p. 12770. , 1995PhRvB.5212770G 10.1103/PhysRevB.52.12770Lide, D.R., (1991) CRC Handbook of Chemistry and Physics, , 72 CRC Press Boca Rato
Photothermally Modulated Magnetic Resonance Applied To The Study Of The Magnetic Phase Transition In Gadolinium Thin Films
No full textWe explore the photothermally modulated magnetic resonance technique to investigate gadolinium thin films deposited on fused quartz substrate, as a function of thickness and thermal treatment, around the magnetic phase transition temperature. It has been observed that the maximum amplitude of the photothermally modulated magnetic resonance (PM-MR) signal takes place near the phase transition temperature, similarly to the magnetocaloric effect, for which Gd has been the prototype material. The reason is that both depend on the temperature derivative of the magnetization, which maximizes at the phase transition. Besides, there is a narrowing of transition with thermal treatment, confirming that thermal treatment stabilizes the film structure. For frequency scan measurements, the heat diffusion in a two-layer system was considered, and a depth profile study was carried out in order to investigate heterogeneities along the film thickness. From the PM-MR response as a function of the modulation frequency it was possible to estimate the thermal properties of the Gd film. Magnetization, X-ray and electron spin resonance measurements were used to complement the analysis and support the conclusions. © 2011 Elsevier B.V. All rights reserved.520936343640Ohring, M., (1991) The Materials Science of Thin Films, , Academic Press New YorkPrutton, M., (1964) Thin Ferromagnetic Films, , Butterworth WashingtonPoole, Jr.C.P., (1983) Electron Spin Resonance, , John Wiley & Sons New YorkAbragam, A., Bleaney, B., (1986) Electron Paramagnetic Resonance of Transitions Ions, , Dover New YorkOrth, T., Netelmann, U., Pelzl, J., (1988) Appl. Phys. Lett., 53, p. 1979Romano, J.A., Mansanares, A.M., Da Silva, E.C., Vargas, H., (1994) J. Phys., 4, pp. C7-667Meckenstock, R., Spodding, D., Pelzl, J., (2002) J. Magn. Mater., 240, p. 83Pecharsky, V.K., Gschneider, Jr.K.A., (1997) Phys. Rev. Lett., 78, p. 4494Foldeaki, M., Schnelle, W., Gmelin, E., Bernard, P., Koszegi, B., Giguere, A., Chahine, R., Bose, T.K., (1997) J. Appl. Phys., 82, p. 309Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , Institute of Physics Series in Condensed Matter Physics BristolMorelli, D.T., Mance, A.M., Mantese, J.M., Micheli, A.L., (1996) J. Appl. Phys., 79, p. 373Gadioli, G.Z., Rouxinol, F.P., Gelamo, R.V., Dos Santos, A.O., Cardoso, L.P., De Moraes, M.A.B., (2008) J. Appl. Phys., 103, p. 093916Recarte, V., Pérez-Landazábal, J.I., Sánchez- Alárcos, V., Chemenko, V.A., Ohtsuka, M., (2009) Appl. Phys. Lett., 95, p. 141908Solzi, M., Pernechele, C., Ghidini, M., Natali, M., Bolzan, M., (2010) J. Magn. Magn. Mater., 322, p. 1565Pelzl, J., Netzelmann, U., (1989) Topics in Currents Physics: Photoacoustic, Photothermal and Photochemical Processes at Surfaces and in Thin Films, p. 313. , P. Hess, Springer-Verlag BerlinGuimarães, A.O., Soffner, M.E., Mansanares, A.M., Coellho, A.A., Magnus, A., Carvalho, G., Pires, M.J.M., Da Silva, E.C., (2009) Phys. Rev. B, 80, p. 134406Guimarães, A.O., Soffner, M.E., Mansanares, A.M., Coellho, A.A., Magnus, A., Carvalho, G., Pires, M.J.M., Da Silva, E.C., (2010) J. Appl. Phys., 107, p. 073524Soffner, M.E., Tedesco, J.C.G., Mansanares, A.M., Gadioli, G.Z., Rouxinol, F.P., De Moraes, M.A.B., Da Silva, E.C., (2010) J. Phys. Conf. Ser., 214, p. 012092Nakamura, O., Baba, K., Ishii, H., Takeda, T., (1988) J. Appl. Phys., 64, p. 3614Farle, M., Baberschke, K., (1987) Phys. Rev. Lett., 58, p. 511Bugardt, P., Seehra, M.S., (1977) Phys. Rev. B, 16, p. 1802Chiba, Y., Nakamura, A., (1970) J. Phys. Soc. Jpn, 29, p. 792Freitas, L.R., Mansanares, A.M., Da Silva, E.C., (2003) Rev. Sci. Instrum., 74, p. 735Glorieux, C., Thoen, J., Bednarz, G., White, M.A., Geldart, D.J.W., (1995) Phys. Rev. B, 52, p. 12770Lide, D.R., (1991) CRC Handbook of Chemistry and Physics, , 72nd ed. CRC PressPetrakian, J.P., Ahmed Mokhtar, N., Fraisse, R., (1977) J. Phys. F: Met. Phys., 7, p. 2431Almond, D.P., Patel, P.M., (1996) Photothermal Science and Techniques, , Chapman & Hall LondonTouloukian, Y.S., Buyco, E.H., (1970) Thermophysical Properties of Matter, , IFI/Plenum New York-Washingto
Photoacoustic Spectroscopy Applied To The Study Of Clay Soils
Get PDFThe study of clay soils using photoacoustic spectroscopy was presented. The observation of the photoacoustic spectra showed the transition bands associated with Fe3+ ions in octahedral or tetrahedral symmetry. Rietveld refinements showed that the Al3+ cations were partially substituted by the Fe3+ cations in the octahedral states of kaolinite structure.741 II355357Alexandre, J., Saboya, F., Marques, B.C., Ribeiro, M.L.P., Salles, C., Da Silva, M.G., Sthel, M.S., Vargas, H., (1999) Analyst, 124, p. 1209Ambikadevi, V.R., Lalithambika, M., (2000) Appl. Clay Sci., 16, p. 133Mehra, O.P., Jackson, M.L., (1960) Clays Clay Miner., 7, p. 317Young, R.A., Sakthivel, A., Moss, T.S., Paiva-Santos, C.O., (1995) J. Appl. Crystallogr., 28, p. 366Sugano, S., Tunabe, Y., Kamimura, H., (1970) Multiplets of Transition-Metal Ions in Crystals, , Academic, New YorkAbritta, T., De Souza Barros, F., (1988) J. Lumin., 40, p. 187Abritta, T., Cella, N., Vargas, H., (1989) Chem. Phys. Lett., 161, p. 12Lima, G.A.R., Baesso, M.L., Arguello, Z.P., Da Silva, E.C., Vargas, H., (1987) Phys. Rev. B, 36, p. 9812Rosencwaig, A., Gersho, A., (1976) J. Appl. Phys., 47, p. 64Baesso, M.L., Mansanares, A.M., Da Silva, E.C., Vargas, H., (1989) Phys. Rev. B, 40, p. 188
Photo Acoustic Study Of Plants Exposed To Varying Light Intensity Growth Conditions: Spectral And Morphological Changes
Get PDFIn this paper we describe results of photo acoustic (PA) measurements carried out on various plants exposed to varying light intensity conditions. Depending on the species and light intensity conditions, the PA absorption spectra show differences in peaks associated with pigments and the cuticle. These differences are related to the spatial distribution of the pigments that differs from plant to plant. We have also performed systematic study of oxygen evolution at different wavelengths. The obtained oxygen spectra are equivalent to the action spectra usually acquired by determining the CO2 uptake and energy storage. The intensities of oxygen spectra exhibit differences depending on distinct morphology of plant. © EDP Sciences.125745748Marquezini, M.V., Cella, N., Mansanares, A.M., Vargas, H., Miranda, L.C.M., (1991) Meas. Sci. Technol., 2, p. 396Barja, P.R., Mansanares, A.M., (1998) Instrum. Sci. Technol., 26, p. 209Barja, P.R., Mansanares, A.M., Da Silva, E.C., Magalhães, A.C.N., Alves, P.L.C.A., (2001) Photosynthetica, 39, p. 489Salisbury, F.B., Ross, C.W., (1992) Plant Physiology, , Wadsworth Publishing Company, CaliforniaClark, J.B., Lister, G.R., (1975) Plant Physiol., 55, p. 401Carpentier, R., Larue, B., Leblanc, R.M., (1983) J. Physique Colloque C6, 44 (10 SUPL), pp. 355-360Veeranjaneyulu, K., Charland, M., Charlebois, D., Leblanc, R.M., (1991) Photosynth. Res., 30, p. 13
Thermal Diffusivity Measurements In Vegetable Oils With Thermal Lens Technique
Get PDFThe thermal lens technique to measure the thermal diffusivity in vegetable oils was discussed. The Amazonian species and olive oils were used as samples. The time resolved spectra were measured using an automatic system and the obtained data were used to solve the thermal property of each oil.741 II697699Gordon, J.P., Leite, R.C.C., Moore, R.S., Porto, S.P.S., Whinery, J.R., (1965) J. Appl. Phys., 36, p. 3Andrade, A.A., Tenorio, E., Catunda, T., Baesso, M.L., Cassanho, A., Jenssen, H.P., (1999) J. Opt. Soc. Am. B, 16, p. 395Baesso, M.L., Bento, A.C., Andrade, A.A., Sampaio, J.A., Pecorato, E., Nunes, L.A.O., Catunda, T., Gama, S., (1998) Phys. Rev. B, 57, p. 10545Brown, S.M., Baesso, M.L., Shen, J., Snook, R.D., (1993) Anal. Chim. Acta, 282, p. 711Bento, A.C., Palangana, A.J., Evangelista, L.R., Baesso, M.L., Pereira, J.R.D., Da Silva, E.C., Mansanares, A.M., (1996) Appl. Phys. Lett., 68, p. 3371Pereira, J.R.D., Mansanares, A.M., Palangana, A.J., Baesso, M.L., (1999) Mol. Cryst. Liq. Cryst. Sci. Technol., Sect. A, 332, p. 3079Shen, J., Love, R.D., Snook, R.D., (1992) Chem. Phys., 165, p. 385Baesso, M.L., Shen, J., Snook, R.D., (1992) Chem. Phys. Lett., 197, p. 25
Thermal Effusivity And Thermal Conductivity Of Biodiesel/diesel And Alcohol/water Mixtures
No full textThe photopyroelectric (PPE) technique was used for the determination of the thermal effusivity and thermal conductivity of biodiesel in diesel and other binary liquid mixtures, precisely, ethanol, and ethylene glycol in water. The front configuration (FPPE) has been explored in the frequency scan approach for obtaining thermal-effusivity values. Measurements show good reproducibility, with uncertainties around 1 % to 2 %, and the results for reference samples, such as ethanol and water, are in good agreement with literature values. The thermal-conductivity values of all samples were determined using the thermal-effusivity data presented here and the thermal-diffusivity data of exactly the same set of samples, reported elsewhere. Based on these results, the different strengths in the molecular interactions related to the several mixtures were evidenced, as proposed by Dadarlat et al. It was shown that, indeed, the thermal effusivity is the property presenting the smallest sensitivity for the molecular association phenomenon, while the thermal conductivity presents an intermediate sensitivity. Nevertheless, the analysis of both properties revealed the existence of weak cohesive interactions among the hydrocarbons of diesel and the esters of biodiesel. © 2012 Springer Science+Business Media, LLC.3310-1118421847Knothe, G., Van Gerpen, J., Krahl, J., (2005) The Biodiesel Handbook, , (eds) AOCS Press Champaign, ILBasha, S.A., Gopal, K.R., Jebaraj, S., (2009) Renew. Sustain. Energy Rev., 13, p. 1628. , 10.1016/j.rser.2008.09.031Sazhin, S.S., Abdelghaffar, W.A., Krutitskii, P.A., Sazhina, E.M., Heikal, M.R., (2005) Int. J. Heat Mass Transf., 48, p. 4215. , 1188.76263 10.1016/j.ijheatmasstransfer.2005.04.007Aliske, M.A., Zagonel, G.F., Costa, B.J., Veiga, W., Saul, C.K., (2007) Fuel, 86, p. 1461. , 10.1016/j.fuel.2006.11.008Morón-Villarreyes, J.A., Soldi, C., De Amorim, A.M., Pizzolatti, M.G., De Mendonça, Jr.A.P., D'Oca, M.G.M., (1977) Fuel, 86, p. 1977. , 10.1016/j.fuel.2007.01.003Almond, D.P., Patel, P.M., (1996) Photothermal Science and Techniques, , Chapman & Hall LondonGuimaraes, A.O., Machado, F.A.L., Zanelato, E.B., Sthell, M.S., Da Silva, E.C., Aranda, D.A.G., (2009) Int. Rev. Chem. Eng., 623, p. 623Castro, M.P.P., Andrade, A.A., Franco, R.W.A., Miranda, P.C.M.L., Sthel, M., Vargas, H., Constantino, R., Baesso, M.L., (2005) Chem. Phys. Lett., 411, p. 18. , 2005CPL.411.18C 10.1016/j.cplett.2005.06.003Delgadillo-Holtfort, I., (2004) Int. J. Thermophys., 2, p. 587Guimarães, A.O., Machado, F.A.L., Da Silva, E.C., Mansanares, A.M., (2012) Thermochim. Acta, 527, p. 125Chirtoc, M., Bentefour, E.H., Antoniow, J.S., Glorieux, C., Delenclos, S., Sahraoui, A.H., Longuemart, S., Buisine, J.M., (2003) Rev. Sci. Instrum., 74, p. 648. , 2003RScI.74.648C 10.1063/1.1520314Chirtoc, M., Miháilescu, G., (1989) Phys. Rev. B, 40, p. 9606. , 1989PhRvB.40.9606C 10.1103/PhysRevB.40.9606Hadj Sahraoui, A., Longuemart, S., Dadarlat, D., Delenclos, S., Kolinsky, C., Buisine, M., (2003) Rev. Sci. Instrum., 74, p. 618. , 2003RScI.74.618S 10.1063/1.1512976Dadarlat, D., Neamtu, C., (2006) Meas. Sci. Technol., 17, p. 3250. , 2006MeScT.17.3250D 10.1088/0957-0233/17/12/008Delenclos, S., Chirtoc, M., Hadj Sahraoui, A., Kolinsky, C., Buisine, M., (2002) Rev. Sci. Instrum., 73, p. 2773. , 2002RScI.73.2773D 10.1063/1.1488147Neamtu, C., Dadarlat, D., Chirtoc, M., Hadj Sahraoui, A., Longuemart, S., Bicanic, D., (2006) Instrum. Sci. Technol., 34, p. 225. , 10.1080/10739140500374088Dadarlat, D., Neamtu, C., (2009) Acta Chim. Slov., 56, p. 22
Heat Source Distribution, Vertical Structure, And Coating Influences On The Temperature Of Operating 0.98 μm Laser Diodes: Photothermal Reflectance Measurements
No full textIn the present work single-quantum-well laser diodes operating at 0.98 μm are investigated by photothermal reflectance microscopy. Temperature maps were obtained for the output facet of all devices studied. Furthermore, the temperature distribution was determined along the cavity (on the ridge) of lasers soldered with the junction side up. Near the facets, the measured temperature was found to be about seven times the bulk's temperature, indicating the presence of an important surface heat source. The signal phase distribution of the laser facet shows the important role of the vertical structure on the heat confinement. Comparison between experiments and calculations shows that the confinement layers (GaAlAs and GaInP) thermal parameters are the principal responsible for the heat propagation in these structures near the active region. The same calculations show the role of the coating (Al2O3) in the heat propagation, and give a quantitative ratio between surface and bulk heat sources. Measurements made on the facet and on the ridge as a function of injection current were found to present a quite similar behavior, leading to the conclusion that thermal effects are strongly dominant in these measurements, masking any carrier or electroreflectance effects. Finally, measurements made under different light output power conditions and under the same injection current conditions showed that the surface heat source is caused by laser light absorption at the facets. © 1998 American Institute of Physics.84734913499Eliseev, P.G., (1996) Quantum Electron., 20, p. 1Epperlein, P.W., (1993) Jpn. J. Appl. Phys., Part 1, 32, p. 5514Mansanares, A.M., Fournier, D., Boccara, A.C., (1993) Electron. Lett., 29, p. 2045Mansanares, A.M., Roger, J.P., Fournier, D., Boccara, A.C., (1994) Appl. Phys. Lett., 64, p. 4Voigt, P., Hartmann, J., Reichling, M., (1996) J. Appl. Phys., 80, p. 2013Batista, J.A., Mansanares, A.M., Da Silva, E.C., Fournier, D., (1997) J. Appl. Phys., 82, p. 423Rosencwaig, A., Thermal wave characterization and inspection of semiconductor materials and devices (1987) Photoacoustic and Thermal Wave Phenomena in Semiconductors, pp. 97-135. , edited by A. Mandelis North-Holland, New YorkForget, B.C., Fournier, D., Gusev, V.E., (1992) Appl. Phys. Lett., 61, p. 2341Tang, W.C., Rosen, H.J., Vettiger, P., Webb, D.J., (1991) Appl. Phys. Lett., 59, p. 1005Nakwaski, W., (1988) J. Appl. Phys., 64, p. 159Cherrak, R., Roger, J.P., Fournier, D., Mansanares, A.M., (1996) Prog. Nat. Sci., 6, pp. S-535Klocek, P., (1991) Handbook of Infrared Optical Materials, , Marcel Dekker, Inc., New YorkEpperlein, P.W., Bona, G.L., (1993) Appl. Phys. Lett., 62, p. 307
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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