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Beamline U11

General Information

Source Type
Bending Magnet

Status
Operational

General User Beamtime
75%

Energy Range Category
Ultraviolet

Energy Range
3-10 eV

Beamline Type
Participating Research Team (PRT)

Technique(s)
Ultra violet circular dichroism

Institution(s)
Brookhaven National Laboratory, Biology Dept.

Research Types
Studies of the solution structure and dynamics of biological macromolecules such as DNA, RNA, proteins and polysaccharides. Circular Dichroism spectroscopy

Contact Information

Spokesperson The person from each beamline who acts as a contact point between the beamline management and NSLS administration. Contact for questions about the beamline scientific program, experimental capabilities, and beamline management.
John Sutherland, Brookhaven National Laboratory, jcs@bnl.gov, 344-3279

Local Contact The beamline staff member who is typically responsible for overseeing the daily operation and maintenance of the beamline. Contact for questions about beamline instrumentation, experimental details, and training.
John Trunk, Brookhaven National Laboratory, trunk@bnl.gov, 344-3406

Beamtime Scheduler The beamline staff member responsible for coordination of beamline schedule every trimester. Contact for questions about beamtime scheduling.
John Trunk, Brookhaven National Laboratory, trunk@bnl.gov, 344-3406

Beamline Phone
631-344-5511

Instrumentation

Beamline Characteristics

Energy Range Mono Crystal or Grating Resolution (ΔE/E) Flux Spot Size (mm) Total Angular Acceptance (mrad)
450 – 4300 (28 – 3 eV) 1200 lines/mm 1 - 3 0.7 – 2 x 1013 ph/sec (@ 1000 mA) 1.0 mm diameter 55H x 10V

Source Type
Bending magnet

Optical System
Monochromator: Modified Wadsworth normal incidence monochromator located 2.7 meters from the source.

Mirror: Spherical concave quartz blank iridium coated mirror; mirror is water cooled and fixed position; 200 mm by 50 mm with 2.8 meter radius; dumps hard x-ray radiation and provides parallel rays to grating; 6 degree angle of incidence; high energy cutoff is 35 eV (350 Angstroms) depending on grating used.

Grating: Spherical concave 4 meter radius focusing grating, vertical focal point at exit slit 2 meters beyond monochromator, horizontal focal point and interaction point 27 mm beyond exit slit; has same dimensions as mirror; 1200 grooves/mm grating is a quartz blank osmium coated ion etched laminar grating, highest efficiency below 11 eV (1100 Angstroms).

Experimental Apparatus
VUV CD Apparatus: an UHV chamber which can be outfitted to perform CD or fluorescence measurements. The Circular Dichroism Spectrometer consists of a Calcium Floride Photoelastic Modulator, a thermostated V-Block sample holder (temperature control from –5 degrees C up to 70 degrees C), and an end on Quartz Photomultiplier Detector. The instrument can perfom standard or time-resolved fluorescence. A conventional magnet is available for Magnetic Circular Dichroism experiments also. Since the sample chamber vacuum can be separated from the beamline via either of two isolation windows, the sample chamber can be purged with dry nitrogen or evacuated to 10-5 Torr.

Computer System Hardware & Software
Intel processor MS-Windows operating system running custom software for beamline control, data acquisition and storage.

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