Materials Chem Diffraction

each peak in X-ray powder diffraction corresponds to…

a particular d spacing in the crystal (family of planes)

in order to see a diffraction peak, the beams produced must be…

in-phase

when beams are in phase, the distance travelled by each must be…

an integer of wavelength

gradual decrease in the intensity of powder x-ray diffraction data as a function of scattered angle is due to…

higher probability of destructive interference as the angle increases

the peak for the largest d spacing will appear at…

the lowest 2theta

d and theta are…

inversely proportional

Peak positions depend on…

unit cell dimensions

Peak intensities depend on…

atomic parameters, atomic number, scattering angle, type of miller planes, sets of miller planes contributing to the same peak, and temperature factor

peak shapes depend on

crystallinity, disorder, and defects in the material

single crystal diffraction produces…

points instead of peaks

indexing

determination of unit cell dimensions from peak positions

the higher the scattering angle…

the lower the peak intensity

what are the 4 parameters included in structure factor

coordinates of atoms, hkl of diffracting planes, atomic number (number of electrons), scattering angle

higher temperature means 

more vibrations and lower peak intensity

lower temperature means

less vibrations and greater peak intensity

species with a greater atomic number (more electrons) (heavier atoms) give…

more intense peaks

species with a lower atomic number (fewer electrons) (lighter atoms) give…

less intense peaks

peaks for smaller unit cells appear at… 

higher 2theta

what is the main information included in CIF?

space group, unit cell dimensions and angles, and the atomic positions

neutron diffraction does not depend on…

atomic number

why is the fact that neutron diffraction does not depend on atomic number an advantage

lighter atoms can be easily studied, and elements with similar atomic numbers can be distinguished

Another advantage of neutron diffraction is that it provides information about…

magnetic order

what are three disadvantages of neutron diffraction?

scarcity, low flux of sources, large quantity of sample needed for obtaining quality data

neutrons in neutron diffraction are being diffracted by…

nuclei (instead of electrons)

unlike x-ray, the neutron scattering power of an atom does not decrease at…

large scattering angles

how does neutron scattering power vary with atomic number?

irregularly 

the neutron scattering power of an atom is called…

scattering length b

different isotopes of the same element will have…

different neutron scattering powers

what element has a neutron scattering power of zero

V⁵¹

can neutron scattering power be negative

yes