"Crystal growth is a science and an art"
Margaret (Peggy) C. Etter
XCL Advisory Committee:
Prof. Wayne L. Gladfelter, Prof. William B. Tolman, Dr. Victor G. Young, Jr.
Department of Chemistry
192C Kolthoff Hall, 207 Pleasant Street S. E.
Minneapolis, MN 55455, USA
Phone : +1 (612) 625-6897
Fax : +1 (612) 626-7541
Exciting Upcoming Crystallographic Events:
ACA Annual Meeting Walt Disney World, Florida, USA. 28 May-2 June 2005
International School on Mathematical and Theoretical Crystallography 20-24 June 2005, Nancy (France)
XX Congress of the International Union of Crystallography Florence, Italy, August 23 - 31, 2005
ICXOM 2005 - 18th International Conference on X-ray Optics and Microanalysis. Frascati (Rome), Italy. 25-30 September 2005
International Conference on Neutron Scattering 2005, 27th November - 2nd December 2005, Sydney, Australia
The Structure Biology of Large Molecular Assemblies the 38th crystallographic course at the Ettore Majorana Centre, Erice. 9 to 18 June 2006
SAS2006 - The XIII-th International Conference on Small-Angle Scattering. Kyoto, Japan. 9-13 July 2006
PNCMI 2006 - The sixth International Workshop on Polarised Neutrons in Condensed Matter Investigations. Berlin, Germany. 25-28 September 2006
Engineering of Crystalline Materials Properties: State-of-the-Art in Modeling, Design, and Applications, the 39th crystallographic course at the Ettore Majorana Centre, Erice, 7 to 17 June 2007
Chillie, © XCL of UMN
ACA Golden Anniversary Meeting - St. Paul, MN
We are investigating merohedral and non-merohedral twins. Especially interesting to us is twinning connected to reversible phase transitions. CCD-based area detectors such as used in our laboratory are a superior tool for unraveling tangled reciprocal lattices of twins (see figure below).
Left: Non-merohedral Twin
h0l section for
Cp*W(NO)(OMe)(h 2- O=C(Me)CH=CPh).
Right: 'Chameleon' Twin
h0l section for
[N(CH3)4]4Ge9O26H12 × 14 H2O
We have developed software (UNTWIN) that allows for correction of intensity data in the case of non-merohedral twinning. Our program has proven very useful in this endeavor and a version running on SGIs is available. A PC test version is available.
Here is a talk on twinning which was given by V. G. Young, Jr. as tutorial and workshop during the 11th Bruker-Nonius Area Detector User's Meeting in Madison, WI 2001 and a talk given at the 2001 ACA meeting in the 'Diffraction Methods in Undergraduate Education' session.
Two key publications on non-merohedral and 'chameleon' twinning are:
[N(CH3)4]4H12Ge9O26 × 14 H2O. A. Tripati, V.G. Young, Jr.,G.M. Johnson, C.L. Cahill, and J.B. Parise. Acta Cryst. C55, 496 (1999).
Composition, Stability, and Structure of a New Member of the Aenigmatite Group. Na2Mg4+XFe 2-2X 3+ Si6+XO20, synthesized at 13-14Gpa. T. Gasparik, J.B. Parise, R.-J. Reeder, V.G. Young, Jr., W.S. Wilford. Am. Mineralogist 84, 257 (1999).
Some twinned beauties
The XCL has two Bruker-AXS platform diffractometers with CCD area detectors and sealed-tube 3-KW X-ray generators. The single crystal instruments are controlled by PC computers and are equipped with low temperature devices. An Oxford Cryostream Cooler allows us to investigate samples in a temperature range between 80 and 300 K. Data are analyzed on Windows 2000 workstations loaded with the SHELXTL V6.10 crystallographic software package from Bruker-AXS for structure solution, refinement and graphical presentation. Site-wide licenses are available for other departmental computers. In addition, program suites WINGX and PLATON, the Cambridge Structural Database (CSD), and the Inorganic Crystal Structure Database (ICSD) are available for site users.
The XCL accepts samples for structural analysis from colleges and universities, as well as from industry. The XCL specializes in samples that suffer from twinning, small size or solvent loss. Please contact us for questions concerning the submission procedure (download sample submission form).
Annually, we teach an X-ray crystallography class which covers theory and prepares students to carry out their own structural analyses. Students and postdocs with previous experience in X-ray crystallography may also become facility users.
1) Clients of our facility receive by email a full report file and a CIF (crystallographic information file) which is required by most journals.
2) All samples are retained by our facility for one month before disposal. Should a client wish a sample returned, he or she should request it with submission.
Nermeen Aboelella, Jessica Allen, Bill Brennessel, Laurie Breyfogle, Eric Brown, Michael Bukowski, Jason Burney, Joon Chatterjee, Dabing Chen, Nicholas Denny, Kevin Erickson, Angela Follett, Derek Fox, Jonathan Frisch, Joe Fritsch, Sarah Michelle Gellar, Yuchuan Gong, Brendan Gordon, Glen Gullickson, Jason Halfen, Benjamin Hamilton, Chuan He, Lyndal Hill, Erin Hilton, Sungjun Hong, Robert Jilek, Sarah Kliegman, Eric Klinker, Alexey Koposov, Benjamin Kucera, Sachin Lohani, Enxian Lu, Kari McGee, Jason Myers, Bill Ojala, Paul Oldenburg, Brian Olmsted, Alicia Peterson, Anne Reynolds, Jan-Uwe Rohde, Julia Rossini, Galen Sedo, Airon Soegiarto, Victor Sussman, Dong Wang, Zhiyong Wang, Dan Wherritt, Elisey Yagodkin, John York