#################################################### # Hyunjung Kim # requesting 7 days, at minimum=4 days # beamline 34ID-C, Mapping of deformation field of CdS dots in Zeolite microcrystals # instrument 34ID-C coherent #################################################### # top:/home/www/beamtime-requests/req01126.txt # UNICAT Member Beam Time Request #1126 # created Wed Apr 25 11:20:14 CDT 2007 #################################################### apsrun: 2007-01 beamline: 34ID-C collaboration: Yes collaborator_Paul: ON contact: hkim@sogang.ac.kr days: 7 description: It has drawn continuous attention to organize microcrystals [1] in the form of uniformly aligned and closely packed layers on substrates for potential applications of bio- and materials science. Some successful methods have been demonstrated for organizing microcrystals with closely packed mono- and multilayers on glass and other substrates through various well-defined covalent and ionic linkages [2], using zeolite crystals as model microcrystals [3]. Zeolites are a class of crystalline aluminosilicate minerals having uniform and regularly spaced pores with the dimension of 0.3-1.5nm. They have been widely used in industry as catalysis, ion exchangers and adsorbents [4]. These crystals also have potential applications as nuclear waste scavengers and are useful as quantum confinement hosts for semiconductor materials. There have been a lot of efforts made in the synthesis of new zeolite crystals and related molecular sieves during the last several decades. Recently there have been successful synthetic methods invented for the production of CdS quantum dots chemically incorporated in pores of zeolite crystals by one of us. However, there are no direct ways yet to measure how well CdS quantum dots incorporated into the pores and whether lattice strain due to confinement effect appears. Unfortunately it is not easy to measure by TEM since zeolite crystals are very easily damaged by electrons. Coherent X-ray diffraction (CXD) is an emerging technique to obtain three-dimensional images of internal density distribution of crystals [5]. When the object is illuminated by coherent x-rays, the oversampled diffraction pattern can be inverted to give real space images of the sample [6]. CXD is a strong analytic method for nondestructive measurement of internal structures of materials. In this study, we are planning to measure CXD on zeolite microcrystals and those having CdS quantum dots in order to get information on internal density distribution and finally to map deformation field of stress or strain due to CdS quantum dots. We have some preliminary results taken at the beamline 34ID-C in the last run (Aug. 2006). The zeolite Y used in this study is constructed by interconnecting sodalite units. We synthesized zeolite Y with the average apex-to-apex length of 2 micrometer. We were able to get coherent diffraction patterns on (111) direction for zeolite Y and for those having CdS quantum dots. We are planning to measure the zeolite Y crystals and those having CdS quantum dots with improved beamline stabilities (already we got informed that they have been fixed.) and employed with 9-10 keV to minimize the absorption of the samples in order to get phase maps through the zeolite crystal at the different parallel planes. [1] T. D. Clark, J. Tien, D. C. Duffy, K. E. Paul, G. M. Whitesides, J. Am. Chem. Soc. 123, 7677 (2001). [2] A. Kulak, Y.-J. Lee, Y. S. Park, K. B. Yoon, Angew. Chem. Int. Ed. 39, 950 (2000). [3] J. S. Lee, Y-J. Lee, E. Lee Tae, Y. S. Park, K. B. Yoon, Science 301,818 (2003). [4] M. E. Davis, Nature 417, 813 (2002). [5] M. A. Pfeifer, G. J. Williams, I. A. Vartanyants, R. Harder, and I. K. Robinson, Nature, 442, 63 (2006). [6] William, G. J, Pfeifer, M. A., Vartanyants, I. A. & Robinson, I. K., Phys. Rev. Lett. 90, 175501 (2003). equipment_required: experiment: Mapping of deformation field of CdS dots in Zeolite microcrystals foreign_nationals: Hyunjung Kim, Youngsuk Byun hazards: N/A instrument: 34ID-C coherent instrument_other: minimumdays: 4 name: Hyunjung Kim nonmembers: Hyunjung Kim, YoungSuk Byun submit: Submit unacceptable_dates: This proposal is for 2007-2. From July 1 to the beginning of August will be good. z34ID_change_undulator: yes z34ID_details: z34ID_parasitic: yes #REMOTE_HOST: r19035.sogang.ac.kr #REMOTE_ADDR: 163.239.202.35 #CONTENT_LENGTH: 4097 #HTTP_REFERER: http://www.uni.aps.anl.gov/admin/unireq.html #HTTP_USER_AGENT: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; MathPlayer 2.0; InfoPath.1)