X-ray diffraction Biophysics

W. K. Röntgen (1845 – 1923) Wife’s hand

Ruhmkorff inductor

X-ray tube with rotating anode

Syncrotron in Grenoble

X-ray spectrum of rhodium Λ min K series Å (Duane – Hunt limit) White radiation Bremsstrahlung

Moseley-law σ= 1 for K lines σ= 7.4 for L lines

Diffractometer Note: diffraction is a special geometry dependent spectroscopy

X-ray diffraction facility

Laue diagram Condition for constructive interference: Δ = AD - BC Incident beam X Z Y α0α0 β0β0 γ0γ0

Diffraction pattern of a crystal

X-ray pattern of whale myoglobin

Debye-Scherrer method

Bragg scattering condition kλ= 2dsinδ

Diffraction from 2-D lattice Incident beam Reflected beam

Sources of secondary X rays zero order third order P Row of scatterers 1 1’ Note: If the number of scatterers increases the diffraction pattern becomes sharper

Continuous helix

Diffraction pattern of continuous helix /P P: pitch of helix

X-ray diffraction of helix structure 1/R +1 1/p

Generation of diffraction pattern 14.3 nm

Striated muscle Relaxed state Rigor state

Sarcoplasmatic reticulum

I4-1 supernova