| CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
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Chemical Quenching of Positronium in CuO/Al2O3 Catalysts |
| ZHANG Hong-Jun, LIU Zhe-Wen, CHEN Zhi-Quan**, WANG Shao-Jie**
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Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072
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ZHANG Hong-Jun, LIU Zhe-Wen, CHEN Zhi-Quan et al 2011 Chin. Phys. Lett. 28 017802 |
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Abstract CuO/Al2O3 catalysts were prepared by mixing CuO and γ−Al2O3 nanopowders. Microstructure and chemical environment of the catalysts are characterized by positron annihilation spectroscopy. The positron annihilation lifetime measurements reveal two long lifetime components τ3 and τ4, which correspond to ortho−positronium (o-Ps) annihilating in microvoids and large pores, respectively. With increasing CuO content from 0 to 40 wt%, both τ4 and its intensity I4 show significant decrease, which indicates quenching effect of o−Ps. The para-positronium (p-Ps) intensities derived from multi-Gaussian fitting of the coincidence Doppler broadening spectra also decrease gradually with increasing CuO content. This excludes the possibility of spin-conversion of positronium. Therefore, the chemical quenching by CuO is probably responsible for the decrease of o-Ps lifetime. Variation in the o-Ps annihilation rate λ4 (1/τ4) as a function of CuO content can be well fitted by a straight line, and the slope of the fitting line is (1.83±0.05)×107 s−1.
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78.70.Bj
82.30.Gg
36.10.Dr
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Received: 24 May 2010
Published: 23 December 2010
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[1] De Diego L F, Gayan P, Garcia-Labiano F, Celaya J, Abad A and Adanez J 2005 Energy and Fuel 19 1850
[2] Chi Y and Chuang S S C 2000 J. Catal. 190 75
[3] Miyahara T, Kanzaki H, Hamada R, Kuroiwa S, Nishiyama S and Tsuruya S 2001 J. Mol. Catal. A 176 141
[4] Luo M F, Fang P, He M and Xie Y L 2005 J. Mol. Catal. A 239 243
[5] Yu J and Savage P E 2000 Appl. Catal. B 28 275
[6] Laperdrix E, Costentin G, Saur O, Lavalley J C, Nedez C, Savin-Poncet S and Nougayrede J 2000 J. Catal. 189 63
[7] Trueba M and Trasatti S P 2005 Eur. J. Inorg. Chem. 17 3393
[8] Jean Y C, Mallon P E and Schrader D M 2003 Principles and Application of Positron and Positronium Chemistry (Singapore: World Scientific) ISBN:981-238-144-9
[9] Tao S J 1972 J. Chem. Phys. 56 5499
[10] Eldrup M, Lightbody D and Sherwood J N 1981 Chem. Phys. 63 51
[11] Ito K, Nakanishi H and Ujihira Y 1999 J. Phys. Chem. B 103 4555
[12] Zhang H J, Wang D, Chen Z Q, Wang S J, Xu Y M and Luo X H 2008 Acta Phys. Sin. 57 7333 (in Chinese)
[13] Jean Y C, Rhee Y, Lou Y, Yen H L, Cao H, Cheong K and Gu Y 1996 Phys. Rev. B 54 1785
[14] Asoka-Kumar P, Alatalo M, Ghosh V J, Kruseman A C, Nielsen B and Lynn K G 1996 Phys. Rev. Lett. 77 2097
[15] Lahtinen J and Hautojarvi P 1997 J. Phys. Chem. B 101 1609
[16] Kirkegaard P, Pederson N J and Eldrup M 1989 Risφ National Laboratory (Roskilde, Denmark)
[17] Saito H and Hyodo T 2003 Phys. Rev. Lett. 90 193401
[18] Shek C H, Gu T S, Lin G M and Lai J K L 1998 Appl. Phys. A 66 413
[19] Wang D, Chen Z Q, Wang D D, Qi N, Gong J, Cao C Y and Tang Z 2010 J. Appl. Phys. 107 023524
[20] Paulin R and Ambrosino G 1968 J. Phys. (France) 29 263
[21] Zhang H J, Chen Z Q, Wang S J, Kawasuso A and Morishita N 2010 Phys. Rev. B 82 035439
[22] Saito H and Hyodo T 1999 Phys. Rev. B 60 11070
[23] Hyodo T, Nakayama T, Saito H, Saito F and Wada K 2009 Phys. Status Solidi C 6 2497
[24] Dlubek G, Fretwell H M and Alam M A 2000 Macromolecules 33 187
[25] Chen Z Q, Maekawa M, Yamamoto S, Kawasuso A, Yuan X L, Sekiguchi T, Suzuki R and Ohdaira T 2004 Phys. Rev. B 69 035210
[26] Chen Z Q, Kawasuso A, Xu Y, Naramoto H, Yuan X L, Sekiguchi T, Suzuki R and Ohdaira T 2005 Phys. Rev. B 71 115213
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