For plate crystals with the long axis normal to the plate surface (anecdotally, this is usually the case), you can use bent loops. Bent loops can be made using tweezers by folding over the loop onto the stem and crimping with the tweezers. When the loop relaxes a bit, it will leave a ~90deg-bent loop, so the crystal can sit on the loop and be shot edge-on in the beam. It takes a bit of time to get it right, but it worked well for me one time.
JPK On Tue, Apr 5, 2011 at 7:29 AM, Jürgen Bosch <jubo...@jhsph.edu> wrote: > What do you consider long ? 200, 300 ? 600 A ? Before shooting try to run > strategy or xplan. Move the detector back to first reliably be able to > determine your cell. Then double your estimated mosaicity and see what > strategy suggests. If you don't get many overlaps (<5%) then try a closer > distance. Don't rotate 1degrees but take 1/2 of the mosaicity. Obviously you > want to make good use of the detector area so adjust the edges to where your > crystal really diffracts. And if that resolution leads to too many overlaps > then limit your resolution and get first a good datasets home. You then can > play with 2theta for a higher resolution dataset. > Another obvious thing to do and you don't mention what reduction program you > use is to let XDS sort your problem out. Unless you collected to high > resolution without being cautious XDS could help. If not, well then you had > your experience and now should know better. > SSRL has options to collect 450 A cells to 3A without much hassle. That was > my largest cell so far. > Jürgen > > ...................... > Jürgen Bosch > Johns Hopkins Bloomberg School of Public Health > Department of Biochemistry & Molecular Biology > Johns Hopkins Malaria Research Institute > 615 North Wolfe Street, W8708 > Baltimore, MD 21205 > Phone: +1-410-614-4742 > Lab: +1-410-614-4894 > Fax: +1-410-955-3655 > http://web.mac.com/bosch_lab/ > On Apr 5, 2011, at 1:05, dengzq1987 <dengzq1...@gmail.com> wrote: > > hello all, > does anyone have the experience of Collecting Data from Long Unit Cell Axes > ? I have a crystal that diffracts to about 4 A. in some direction the spots > overlap. we can't use the data to index .we think it is because that there > is a long unit cell axes. so is there any method to solve this problem? > > best wishes. > > 2011-04-05 > ________________________________ > dengzq1987 -- ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program cel: 773.608.9185 email: j-kell...@northwestern.edu *******************************************
