ABSOLUTE X RAY SCATTERING CROSS SECTIONS OF LIQUIDS AND SOLUTIONS

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1964

OSTI ID:4019683

Shaffer, L B

Absolute measurements of the product of the number density of molecules in a sample and the molecular differential x-ray scattering cross section at small angles was accomplished by comparing the small angle x ray scattering observed from the sample with the scattering observed from a standard sample for which the differential scant ering cross section and number density are known. Three heavy gases were intercompared and used as primary standards. The scattering from solutions and liquids was observed in the identical geometry as the gas scattering, thus eliminating complicated geometric corrections. Single crystal quartz plates 0.0010 in. thick were used as sample holder windows. The three gases gave a calibration of the incident beam and geometry to plus or minus 2%. A scattering 10% in excess of that predicted using thermodynamic relationships was observed for water, ethyl alcohol, xylene, and benzene. Scattering observed from solutions of metmyoglobin was within 3% of the predicted scattering whereas for ribonuclease a 30% excess scattering was observed. The excess is ascribed to aggregation of the molecules in solution. A theory of zero angle x ray scattering from solutions, relating the scattering to the osmotic pressure, is presented and compared with the observed scattering from sucrose and several salt solutions. The sucrose data agree with the theoretical scattering to plus or minus 3%, as a function of concentration, up to 20% solutions. The scattering from NaCl, KCl, and NaNO/sub 3/ also agrees well with the theory. Duplicate protein scattering data on two small angle x-ray machines, one with a slit separation of 10 cm and the other of 50 cm, permit a comparison of the slit height correction factors necessary for the different geometries. However, the location of the focal spot relative to the first slit is the determining factor for the form of the observed rocking curves. A calculation of the rocking curves for several different focal spot locations and sizes is given. When the appropriate weighting functions are used the protein data observed on the two machines agree to within the precision of the measurement. (Dissertation Abstr., 24: No. 9, March 1964)

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-18-020035
• OSTI ID: 4019683
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BENZENE
CHEMISTRY
CROSS SECTIONS
DIAGRAMS
ENZYMES
ETHANOL
GASES
HEMOGLOBIN
LIQUIDS
MEASURED VALUES
MONOCRYSTALS
POTASSIUM CHLORIDES
PROTEINS
QUARTZ
RIBONUCLEIC ACID
RNA-ASE
SCATTERING
SODIUM CHLORIDES
SODIUM NITRATES
SOLUTIONS
STANDARDS
SUCROSE
SUGARS
WATER
X RADIATION
XYLENE