X-ray - Chemistry in Context "This structure has novel...

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Chemistry in Context "This structure has novel features which are of considerable biological interest.” What is this structure and how was it obtained? X-ray diffraction pattern of DNA acquired by Rosalind Franklin.
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CH 12: X-ray Methods Same basic types of experiments as other optical methods: (No Homework) Absorption Diffraction Fluorescence Scattering Methods differ, however, in the instrumentation required and information provided.
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CH 12: X-ray Methods General Attributes Typically used for analyzing solid samples Non-destructive Small and large samples may be analyzed (nanoparticles to martian rocks, jewelery, paintins, etc) Multielement detection Compound and oxidation state specific (Fe 3 O 4 , Fe 2 O 3 ) can be distinguished Good for surface analysis Expensive
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Generation of X-rays
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Concept Te$t The energies of light with 500 nm and 2 nm wavelengths are (A) 3.3 x 10 -31 J and 1.3 x 10 -33 J (B) 4.0 x 10 -28 J and 9.9 x 10 -26 J (C) 4.0 x 10 -19 and 9.9 x 10 -17 (D) 4.0 x 10 -19 J and 9.9 x 10 -17 J 1 mol of 2 nm photons = 6 x 10 7 J
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1 beat of Human Heart 1 J Lifting a book from floor to table 15 J 1 Krispy Kreme Donut 4,157,000 J 1 donut keeps the heart ticking for 1,154 hours! For comparison…. .
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X-ray Sources (A) Bombardment of a target with electrons (B) Exposure of a target to a primary beam of X- rays to generate a secondary beam of X-rays (C) Radioactive source (D) Synchrotron source (National Labs) Sources produce line and continuum spectra. Continuum X-ray spectra are called “white radiation” or bremsstrahlung radiation.
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Concept Te$t New Rules! In the event of a dispute, two teams can wager up to $3. The winner takes the $3 from the loser. The reaction between oxygen and the iron in hemoglobin causes a dramatic change in its absorbance. Suppose you wanted to measure the kinetics of the reaction. Choose the technique below that is most suited for monitoring the appearance of HbO 2 and disappearance of Hb in time.as O 2 is mixed with Hb. (A) Atomic absorbance (B) Photodiode array visible spectroscopy (C) Magnetic sector MS (D) Photomultiplier tube visible spectroscopy
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X-ray Sources X-ray tube Electrons produced at a heated cathode are accelerated toward a metal anode by a potential of 100 kV.
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This note was uploaded on 02/23/2011 for the course CHEM 4181 at Colorado.

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X-ray - Chemistry in Context "This structure has novel...

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