ULTRACENTRIFUGE STUDIES WITH ABSORPTION OPTICS. 3. A SPLIT-BEAM PHOTOELECTRIC, SCANNING ABSORPTION SYSTEM.

摘要: Abstract An automatic split-beam scanning absorption system for the ultracentrifuge is described. The consists of a four-speed drive assembly which controls rate movement photomultiplier across magnified image cell. housing contains turret permits selection any six different slits in front photocathode. High resolution achieved by use about 35 μ width. Double sector cells are used rotor so that two light bursts strike quick succession followed long dark period while completes one revolution. cell filled such way first pulse after corresponds to solvent compartment and second solution interest. A logarithmic circuit converts voltages scale. electronic switching arrangement incorporated separation pulses routing signals into holding circuits, reference other sample. outputs circuits representing logarithms intensity through compartments then fed difference amplifier where subtraction achieved. resulting signal directed recorder plots automatically optical density as function position In this single beam passing vacuum chamber split chopping action give individual stored compared. Experiments presented demonstrate compensates nonuniform illumination from inadequacies itself. Performance tests given show linearity recording terms liquid sample shown perform satisfactorily accomplished 1 μsecond thereby permitting occur within 6 μseconds when operates at 60,000 rpm. Various applications given. These include sedimentation coefficient determinations well evaluations concentrations molecular weight equilibrium technique. both types experiments results were excellent agreement with known values. Other analyses interacting systems transport methods measurement small differences coefficients.