Table I.

Electron Spectroscopies	Information available	Probe	Detected	Lateral Resolution	Information Depth	Depth Resolution
Auger electron spectroscopy (AES)	• Surface composition of individual large nanoparticles or distribution of smaller nanoparticles (depending on spatial resulution of specific instrument). • Enrichment or depletion of elements at surface • Presence and/or thickness of coatings and/or contaminants	electrons (~ 3 to 20 kV)	Auger electrons	≈ 10 nm	≈ 10 nm	≈ 2 nm

X-ray photoelectron spectroscopy (XPS)

• Analysis of a collection of particles deposited on a substrate or other support. • Surface composition and chemical state • Presence and nature of functional groups on the surface • Enrichment or depletion of elements at surface • Presence and/or thickness of coatings or contaminats • Nanoparticle Size (when smaller than ~ 10 nm, can sometimes determine average particle size when too small to be detectred by other methods or in complex matrix.) • Electrical properties of nanopartlcles and coatings

X-rays

Photoelectrons

≈ 2 μm

≈ 10 nm

≈ 2 nm

Incident Ion Methods
Secondary Ion Mass Spectrometery (SIMS)	• Usually analysis of a collection of particles or larger individual particles deposited on a supporting substrate. • Presence of surface coatings or contamiinants on collections of nanoparticles • Functional groups on surface	Ions (~ 3 - 20 kV)	sputtered ions	≈ 50 nm (inorganic) > 200 nm (organic)	≈ 1 nm	≈ 1 nm (inorganic) ≈ 10 nm (organic)

Low energy ion scattering (LEIS)

• Presence of ultra thin coating or contamination • Effects of size

Ions (~ 2 to 10 kV)

elastically scattered ions

≈ 100 μm

≈ 10 nm

≈ 0.2 nm

Scanning Probe Microscopies
Scanning Tunneling Microscopy (STM)	• Electrical characteristics of individual nanoparticles • Nanoparticle formation and/or size distribution of particles deposited or grown on a surface	stylus	tunneling current	≈ 1 nm	≈ 10 nm

Atomic force microscopy (AFM)

• Shape, texture and roughness of individual particles and their distribution for an assembly of particles • When particle structure is known, can provide information about crystalligraphic orientation

stylus

force or displacement

≈ 1 nm

≈ 10 nm