PAINTS AND PIGMENTS 2

whats a major factor in the comparison of paints and pigments

colour perception

what does perception of colour rely on

simultaneous contrast

what are colours refered to as

RGB

what is RBG

stanardised digital space in identification of colour

what is microspectrophotometry

microscope and spectrometer combined

what does microspectrophotometry do

charateristics of distribution wavelengths

what does microspectrophotometry capture

magnified visual and spectroscopic patterns

what does microspectrophotometry combine

IV visible NR digital imaging with colorimetry

what is the most common paint evidence

automotive

what does a comparison microscope make a note of with paint

• colour

  • texture

• layer sequence

• relative layer thickness

• pigment size and distrivution

• defects

what are some defects that can be seen in pain

weathering dirt and solvent traps

what are the 4 ways paint can be observed under comparison micro

• cross section

• thin peels

• wedge cut

• stair step exposure

what is the secodn most essential tool in forensic paint analysis

IR spec

why is IR spec good

• quick

• minimal destruction

• little sample prep

how is IR spec run

in transmitted or ATR

what is ATR

attenuated total reflection

what is a limitation for IR

pigments below cut off and LOD cant be seen

what can raman do that IR cant

discriminate crystalline polymorphs

what does fluorescence mean

absorbance of radiation at one energy and remission at a different

what is created when a electron from the inner K shell is ekected from the atoms due to being excited

a vacancy

what happens once a vacancy is created

atoms from L or M shell fills it

what deos XRF stand for

xray fluoresence

what are 3 advantages of using XRF

handheld, non destructive, no sample prep

how is nano structure characterised

studying chemical and physical properties

what are the 2 techniques useed to asses nano structure

microscopy and diffraction

what are 3 examples of microscopy

scanning electron, transmission electron and atomic force

what method can you use to achieve a higher resolution

electron microscopy

when does beam damage occur

with sensitive samples

what does electron microscopy show

elemental com

what does combing electron micro and XRF increase

discirminating power

what scattering is used in TEM

elastic diffraction

what scattering is used in SEM

inelastic backscattering

what scattering is used in spectroscopy

inelastic energy loss

does sem or xrf require a larger sample size

xrf

does sem or xrf have a lower lod

xrf

what does this represent

braggs law

what is braggs law for

understanding conditions required for diffraction

what does braggs law show

arrangements of atoms in crystal structure and how they stack

what is n in braggs law

integer (1)

what is d in braggs law

interplanar spacing

what is theta in braggs law

angle between plane and beam

what can be controlled in braggs law

theta and lambda

what does this spacing show us

interplanar spacing

what does this angle show us

angle between plane and beam

what can diffraction determine (4)

• lattice parameters

• phase composition

• crystal structure

• crystallite size

how does diffraction determine lattice parameters

indexing position of peaks

how does diffraction determine phase compostion

given relative amount of voerlayed diffraction

how does diffraction determine crystal strcuture

redefining whole diffraction pattern

how does diffraction determine crystallite size

looking at peak broadening