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Scanning tunneling microscopy study of heavy ion tracks and a latent track nuclear detector
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Nut/. Tmc~RmUm.M,em'., Vol. 22, Nm I-4, pp. 8.%417,1993 E~evter~ Lat l~mted ia Ohm lktmm. 0969-1Y/11/~$6.00+.00
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SCANNING TUNNELING MICROSCOPY STUDY OF HEAVY ION TRACKS AND A LATENT TRACK NUCLEAR DETECTOR TANGXIAOWmand ZtlAIPl~OJ* Institute of High Energy Physics, AcademiaSinica, Beijing 100039, P.O. Box 918, P. R. China *Instituteof High Energy Physics,AcademiaSinica,Beijing 1000g0, P.O. Box 2732, P.R. China
ABSTRACT The experimental results of scanning tunneling microscopy study of heavy ion tracks are .re.po.rte~. A new principle of nuclear detector is proposed that primary latent tracks of ~cment nuclei .are m..e.e.~uredd i r ~ . y using sce4ming tunneling microscopy. The new detector as a super-mgn spauaJ resolution about 30-50A. KEYWORDS
STM; heavy ion tracks; nuclear detector; latent track; spatial resolution. Detailed understanding of the radiation damage and reparation from interaction between the vy char~ed p.article and solid material is an important topic in material science, but it is ffiMc,~ltto. mv~tigate such small regions of.dmmaged material directly. Braunshausen eta/. t.yay) ana w ~ o u e t al (1989) have reported their observation of heavy ion latent tracks in zzrcon ano metal compouno using high-resolution transmission electron microscope ~ . But it is known that the electron beam might cause the track fading in the sample.
!]~
With the advent of STM and AFM it becomes possible to observe directly the radiation of.heavy ion tr~c._kson an aw.mic scale. At first the low energy heavy zon tracks were s.,.u~.eo, wus~...et aL .(19.8~;) llave given results of low energy heavy zon bombarded PbS and ~l/~ztJ. oy ~XM. t'one et al. (1991) have reported STM observation of local damages induce/[ on HOPG surface by low energy heavy ion implantation. For high energy ion tracks we (Zhai Pengji e t a / . , 1992) reported our observation of high energetic heavy ion impacts on MS~I2,. surface by STIr.. The MoS2 sample was irradiated by 13.4MeV/N Au ion beam at . . . ' uennany, anaa_z~ surface, was measured by STM at ikijing Laboratory of Electron M l ~ . rne :~rM images ws.th.regular atomic structure on unbombarded MoS2 surface were oo~.rv.ed and the defects szmzlar to the damaged tracks were not found. Many STM zmages wlzn regular atomic arrangement and the craters of radiation damage with sharp
85
86
TANG XIAOWEI and ZHAI PENGJ
boundaries due to single-ion impacts on the surface of bombarded MoS, were obtained such as Fig. 1..The dimensions of 116 craters profiles on two-ciimensional STI~I image varied from below 5A to above 50A, but most of them were 10-35A. Not only atomic structures of the original surface, but also the structures of craters and local rearrangements at the bottom of the craters were clearly shown in the STM images. In STM images of different size an approximately 100 % correlation between incident ion recording and number of craters was estimated.
Fig. 1. Three-dimensional STM image on the surface of MoS 2 bombarded by high-energy Au ions. Till now the principles of all nuclear detectors are based on the physical or chemical proce~es which amplify the primary latent tracks of incident nuclei into visible tracks in detectors (Segre, 1977). The spatial resolution of all detectors can not satisfy the needs of the future ultra-high energy experiments since the products in the final states of the nuclear reactions are highly concentrated in space. In relativistic heavy ion collisions, many projectile fragments among the reaction products are emitted in a very narrow forward cone. It is known that the opening angle of the cone 0 _< 0.2/E, where E is the energy per nucleon of incident nuclei in GeV/N (Adamovich, et al.,). For E ffi 200 GeV/N, 0 ~ 1 mrad. For E ffi 20 TCV/N, it is expected that 0 ~ 10/~rad. It is clear that new detectors with super high spatial resolution are needed for the detection of these fragments. We propose a new principle of nuclear detector with super-high spatial resolution, the incident nucleus is recorded by a solid material by producing a radiation damage region on the surface of the material which is a part of primary latent track of incident nucleus, then the radiation damage region is scanned and measured directly by STM. The unique features of the new detector are (a) no etching is used and fo) the tracks are measured using STM. For insulator materials the atomic force microscope (AFlVl) can be used. In the sixties Price and Walker (1962) measured the primary latent track using electron microscope and they encountered the difficulty of track fading due to the irradiation of elec-
STM STUDY OF HEAVYION TRACKS
87
iron beam. The p~l~ress of STM and AFM enables us to use STM and AFM instead of electron microscope. Since the tunneling current of STM and AFM is very small, there is no track fading problem during the processes of scanning and measurement. The detector directly detects the primary tracks of incident nuclei without any amplification, therefore it has a super-high spatial resolution. According to the experimental data.(Zhal" Pengji, et al., 1992) the two track resolution of the detector is estimated to be 30A-50A (Tang Xiaowei, et al., 1992), which is about two to three orders of magnitude better than any nuclear detectors nowadays. ACKNOWLEDGEMENTS We would like to thank GSI for providing the ion beam, Drs. J. Vetter and R. Spohr for irradiating the MoS2 specimen, BLEM for help and support and Lu Feng for measurement. REFERENCES Adamovich, M.I., M.M. Aggarwal., R. Arora., Y.A. Alexandrov., S.A. Asimov., E. Basova., K.B. Bhalla., A. Bhasin., V.S. Bhatia., R.A. Bondarenkov., T.H. BurneR., X. Cal., L.P. Chernova., M.M. Chemyavsky., B. Dressel., E.M. Friedlander., S.I. Gadzhieva., E.R. Ganssauge., S. Garpman., S.G. Gerassimov., A. Gill., J. Grote., K.G. Gulamov., U.G. Gulyamov., S. Hackel., H.H. HecIanan., B. Jakobsson., B. Judek., S. Kachroo., F.G. Kadyrov., H. Kallies.," L. Karlsson., G.L. Kaul., M. Kaur., S.P. Kharlamov., V. Kumar., P. Lal., V.G. Larionova., P.J. Lindstrom., L.S. Liu., S. Lokanathan., J. Lord., N.S. Lukicheva., L.K. Mangotra., H.V. Maslennikova., I.S. Mittra., E. Monnand., S. Mookerjee., C. Mueller., S.H. Nasyrov., W.S. Navomy., G.I. Orlova., I. Otterlund., H .S. Palsania., N.G. Pere-~d_ko., S. Persson., N.V. Petrov., W.Y. Qian., R. Raniwala., S. Raniwala., N.K. Rao., J.T. Rhee., N. Saidkhanov., N.G. Salmanova., W. Schulz., F. Schussler., V.S. Shuida., D. Skelding., K. Soderstrom., E. Stenlund., R.S. Storey., J.F. Sun., L.N. Svechnikova., M.I. Tretyakova., T.P. Trofimova., H.Q. Wang., Z.O. Weng., R.J. Wilkes., G.F. Xu., D.H. Zhang., P.Y. Zheng., D.C. Zhou and J.C. Zhou (1989). Phys. Rev. C40, 66-71. Barbu, A., A. Dunlop., R.S. Averback., R. Spohr and J. Vetter (1989). Latent tracks induced by high electronic excitations in a metallic compound? GSI Scientific Reports, 221. Braunshausen, G. and L.A. Bursill 0989). Structure of heavy-tracks in zircon. GSI Scientific Reports, 219. Porte, L., C.H. deVilleneuve and M. Phaner (1991). Scanning tunneling microscopy observation of local damages induced on graphite surface by ion implantation. J. Vac. $ci. Technol., Bg, 1064-1067. Price, P.B. and R.M. Walker (1962). Observations of charged-particle tracks in solids. Appl. Phys. 33, 3400-3412. Segre, E 0977). Nuclei and Particle (2nd edtion) Benjamin Inc. Tang, X.W., J.E. Yao and P.J. Zhai (1992). A nuclear detector with super-high spatial resolution. Nuclear Instruments and Methods in Physics Research A320, 396-397. Wilson, I.H., N.J. Zheng., U. Knipping and S.T. Tsong (1988a). Scanning tunneling microscopy of an ion-bombarded PbS (001) surface. Appl. Phys. Lett. 21, 2039-2041. Wilson, I.H., N.J. Zheng., U. Knipping and S.T. Tsong (1988b). Effects of isolated atomic collision cascades on SiO./Si interfaces studied by scanning tunneling microscopy. Phys. Rev. B38, 8444-8455 Zhai, P.J., E Lu., X.W. Tang., J. Wei., J. He., G.Y. Shang and J.E. Yao (1992). Observation of radiation damage of energetic heavy ions impacts on MoS2 surface by scanning tunneling microscopy. Science in China A 11, 1207-1211.
Nut/. Tmc~RmUm.M,em'., Vol. 22, Nm I-4, pp. 8.%417,1993 E~evter~ Lat l~mted ia Ohm lktmm. 0969-1Y/11/~$6.00+.00
]~rggmon
SCANNING TUNNELING MICROSCOPY STUDY OF HEAVY ION TRACKS AND A LATENT TRACK NUCLEAR DETECTOR TANGXIAOWmand ZtlAIPl~OJ* Institute of High Energy Physics, AcademiaSinica, Beijing 100039, P.O. Box 918, P. R. China *Instituteof High Energy Physics,AcademiaSinica,Beijing 1000g0, P.O. Box 2732, P.R. China
ABSTRACT The experimental results of scanning tunneling microscopy study of heavy ion tracks are .re.po.rte~. A new principle of nuclear detector is proposed that primary latent tracks of ~cment nuclei .are m..e.e.~uredd i r ~ . y using sce4ming tunneling microscopy. The new detector as a super-mgn spauaJ resolution about 30-50A. KEYWORDS
STM; heavy ion tracks; nuclear detector; latent track; spatial resolution. Detailed understanding of the radiation damage and reparation from interaction between the vy char~ed p.article and solid material is an important topic in material science, but it is ffiMc,~ltto. mv~tigate such small regions of.dmmaged material directly. Braunshausen eta/. t.yay) ana w ~ o u e t al (1989) have reported their observation of heavy ion latent tracks in zzrcon ano metal compouno using high-resolution transmission electron microscope ~ . But it is known that the electron beam might cause the track fading in the sample.
!]~
With the advent of STM and AFM it becomes possible to observe directly the radiation of.heavy ion tr~c._kson an aw.mic scale. At first the low energy heavy zon tracks were s.,.u~.eo, wus~...et aL .(19.8~;) llave given results of low energy heavy zon bombarded PbS and ~l/~ztJ. oy ~XM. t'one et al. (1991) have reported STM observation of local damages induce/[ on HOPG surface by low energy heavy ion implantation. For high energy ion tracks we (Zhai Pengji e t a / . , 1992) reported our observation of high energetic heavy ion impacts on MS~I2,. surface by STIr.. The MoS2 sample was irradiated by 13.4MeV/N Au ion beam at . . . ' uennany, anaa_z~ surface, was measured by STM at ikijing Laboratory of Electron M l ~ . rne :~rM images ws.th.regular atomic structure on unbombarded MoS2 surface were oo~.rv.ed and the defects szmzlar to the damaged tracks were not found. Many STM zmages wlzn regular atomic arrangement and the craters of radiation damage with sharp
85
86
TANG XIAOWEI and ZHAI PENGJ
boundaries due to single-ion impacts on the surface of bombarded MoS, were obtained such as Fig. 1..The dimensions of 116 craters profiles on two-ciimensional STI~I image varied from below 5A to above 50A, but most of them were 10-35A. Not only atomic structures of the original surface, but also the structures of craters and local rearrangements at the bottom of the craters were clearly shown in the STM images. In STM images of different size an approximately 100 % correlation between incident ion recording and number of craters was estimated.
Fig. 1. Three-dimensional STM image on the surface of MoS 2 bombarded by high-energy Au ions. Till now the principles of all nuclear detectors are based on the physical or chemical proce~es which amplify the primary latent tracks of incident nuclei into visible tracks in detectors (Segre, 1977). The spatial resolution of all detectors can not satisfy the needs of the future ultra-high energy experiments since the products in the final states of the nuclear reactions are highly concentrated in space. In relativistic heavy ion collisions, many projectile fragments among the reaction products are emitted in a very narrow forward cone. It is known that the opening angle of the cone 0 _< 0.2/E, where E is the energy per nucleon of incident nuclei in GeV/N (Adamovich, et al.,). For E ffi 200 GeV/N, 0 ~ 1 mrad. For E ffi 20 TCV/N, it is expected that 0 ~ 10/~rad. It is clear that new detectors with super high spatial resolution are needed for the detection of these fragments. We propose a new principle of nuclear detector with super-high spatial resolution, the incident nucleus is recorded by a solid material by producing a radiation damage region on the surface of the material which is a part of primary latent track of incident nucleus, then the radiation damage region is scanned and measured directly by STM. The unique features of the new detector are (a) no etching is used and fo) the tracks are measured using STM. For insulator materials the atomic force microscope (AFlVl) can be used. In the sixties Price and Walker (1962) measured the primary latent track using electron microscope and they encountered the difficulty of track fading due to the irradiation of elec-
STM STUDY OF HEAVYION TRACKS
87
iron beam. The p~l~ress of STM and AFM enables us to use STM and AFM instead of electron microscope. Since the tunneling current of STM and AFM is very small, there is no track fading problem during the processes of scanning and measurement. The detector directly detects the primary tracks of incident nuclei without any amplification, therefore it has a super-high spatial resolution. According to the experimental data.(Zhal" Pengji, et al., 1992) the two track resolution of the detector is estimated to be 30A-50A (Tang Xiaowei, et al., 1992), which is about two to three orders of magnitude better than any nuclear detectors nowadays. ACKNOWLEDGEMENTS We would like to thank GSI for providing the ion beam, Drs. J. Vetter and R. Spohr for irradiating the MoS2 specimen, BLEM for help and support and Lu Feng for measurement. REFERENCES Adamovich, M.I., M.M. Aggarwal., R. Arora., Y.A. Alexandrov., S.A. Asimov., E. Basova., K.B. Bhalla., A. Bhasin., V.S. Bhatia., R.A. Bondarenkov., T.H. BurneR., X. Cal., L.P. Chernova., M.M. Chemyavsky., B. Dressel., E.M. Friedlander., S.I. Gadzhieva., E.R. Ganssauge., S. Garpman., S.G. Gerassimov., A. Gill., J. Grote., K.G. Gulamov., U.G. Gulyamov., S. Hackel., H.H. HecIanan., B. Jakobsson., B. Judek., S. Kachroo., F.G. Kadyrov., H. Kallies.," L. Karlsson., G.L. Kaul., M. Kaur., S.P. Kharlamov., V. Kumar., P. Lal., V.G. Larionova., P.J. Lindstrom., L.S. Liu., S. Lokanathan., J. Lord., N.S. Lukicheva., L.K. Mangotra., H.V. Maslennikova., I.S. Mittra., E. Monnand., S. Mookerjee., C. Mueller., S.H. Nasyrov., W.S. Navomy., G.I. Orlova., I. Otterlund., H .S. Palsania., N.G. Pere-~d_ko., S. Persson., N.V. Petrov., W.Y. Qian., R. Raniwala., S. Raniwala., N.K. Rao., J.T. Rhee., N. Saidkhanov., N.G. Salmanova., W. Schulz., F. Schussler., V.S. Shuida., D. Skelding., K. Soderstrom., E. Stenlund., R.S. Storey., J.F. Sun., L.N. Svechnikova., M.I. Tretyakova., T.P. Trofimova., H.Q. Wang., Z.O. Weng., R.J. Wilkes., G.F. Xu., D.H. Zhang., P.Y. Zheng., D.C. Zhou and J.C. Zhou (1989). Phys. Rev. C40, 66-71. Barbu, A., A. Dunlop., R.S. Averback., R. Spohr and J. Vetter (1989). Latent tracks induced by high electronic excitations in a metallic compound? GSI Scientific Reports, 221. Braunshausen, G. and L.A. Bursill 0989). Structure of heavy-tracks in zircon. GSI Scientific Reports, 219. Porte, L., C.H. deVilleneuve and M. Phaner (1991). Scanning tunneling microscopy observation of local damages induced on graphite surface by ion implantation. J. Vac. $ci. Technol., Bg, 1064-1067. Price, P.B. and R.M. Walker (1962). Observations of charged-particle tracks in solids. Appl. Phys. 33, 3400-3412. Segre, E 0977). Nuclei and Particle (2nd edtion) Benjamin Inc. Tang, X.W., J.E. Yao and P.J. Zhai (1992). A nuclear detector with super-high spatial resolution. Nuclear Instruments and Methods in Physics Research A320, 396-397. Wilson, I.H., N.J. Zheng., U. Knipping and S.T. Tsong (1988a). Scanning tunneling microscopy of an ion-bombarded PbS (001) surface. Appl. Phys. Lett. 21, 2039-2041. Wilson, I.H., N.J. Zheng., U. Knipping and S.T. Tsong (1988b). Effects of isolated atomic collision cascades on SiO./Si interfaces studied by scanning tunneling microscopy. Phys. Rev. B38, 8444-8455 Zhai, P.J., E Lu., X.W. Tang., J. Wei., J. He., G.Y. Shang and J.E. Yao (1992). Observation of radiation damage of energetic heavy ions impacts on MoS2 surface by scanning tunneling microscopy. Science in China A 11, 1207-1211.