Microscopes |
Optical Microscopy
* History: Introduced by Antony
van Leeuwenhoek (NL) in 1671.
* Characteristics: Visible and
near-UV photons, relatively long λ; Resolution about 2000 Å;
2003, Improved to less than 20 nm using "near-field Raman microscopy"
[@ Hartschuh et al PRL(03)].
@ General references: Imhof & Vanden Bout AJP(03)may [laser-based, RL];
Tsang Opt(15)-a1411 [fundamental quantum limits].
@ Beating the diffraction limit:
Müller & Enderlein PRL(10)
+ Blom & Widengren Phy(10) [image scanning microscopy];
Chu et al PRL(14).
X-Ray Diffraction Microscopy > s.a. X-Rays.
* History: Introduced by
Max Laue in 1912 and used by Lawrence Bragg in 1913.
* Characteristics: Medium-hard
X-rays with energies up to about 10 KeV; Resolution about 500–700 Å.
* Advantages: Good quality images
at atomic or near-atomic scales.
* Disadvantages: A macroscopic
crystal or oriented fiber sample has to be used, due to the low coherent
scattering cross-section and the need to get a reasonably simple image.
Soft X-Ray Microscopy > s.a. X-Rays.
* History: Introduced in the 1950s.
* Advantages: Avoids the
difficulties with the above methods.
Electron Microscopy
* History: Introduced
by Ernst Ruska and Max Knoll (Berlin) in 1932.
* Characteristics: Uses
electrons of energy 5–2000 KeV.
* Disadvantages: Specimen
subjected to cellular disassembly and dehydration, and decoration with heavy
atoms, to avoid the problems related to the high electron-water cross-section
and to improve the contrast.
@ References: Alem et al PRB(09)
+ Klie Phy(09) [new resolution standard];
Marks Phy(13) [unexpected barrier to better resolution].
Scanning Tunneling (Electron) Microscopy
* History: Discussed in
1978, and introduced in 1981 (by Binnig and Rohrer); The first generation
used magnetic levitation (with superconducting bowl) to avoid vibrations;
Later used eddy-current damping; 1996, Four generations by now; 2004,
Crystal imaged on sub-Å scales by exploiting a technique to correct
aberrations.
* Idea: One positions
the tip of an extremely sharp needle (best so far is 3 atoms) so close to
a surface that the wavefunctions of electrons in the tip overlap those of
electrons in the surface, and a tunneling current is established, which is
extremely sensitive to tip-surface separation.
* Characteristics: Allows
to study surfaces at an atomic scale, with a lateral resolution of 1 Å,
and a height corrugation accuracy of 0.01 Å; Initially limited to
conductors, and under a vacuum, now these limitations partly overcome (1996).
@ General references: Binnig & Rohrer SA(85)aug;
Golovchenko Sci(86)apr;
Chen 93;
Nellist et al Sci(04)sep
+ pw(04)sep [aberration correction].
@ Use for placing atoms: Meyer et al PRL(96)
+ pn(96)sep.
@ Watching single atoms move:
Molinàs-Mata et al PRL(98);
Kavanagh Phy(09)
[aberration-corrected transmission electron microscopes];
van Houselt & Zandvliet RMP(10) [time-resolved STM].
Acoustic Microscopy
* History: Proposed by Sergei
Y Sokolov (USSR) in 1949; Serious work on it started in the late 1960s.
* Characteristics: Resolution
200 Å.
@ References: Briggs & Kolosov
09.
Other Types and References
* Field ion microscopy:
The first to achieve atomic resolution; Non scanning, uses a sharp tungsten
needle, and gives an image of atoms on its tip.
* Ion beam microscopy: Can
analyze masses of atomic species that come from a specimen during sputtering;
Resolution 400 Å.
* Microtomography: Developed in 1987; Essentially
3D X-ray microscopy; Resolves micron-sized structures inside (dead) solid objects.
@ Atomic force microscopy:
Binnig et al PRL(86)
+ focus Phy(12);
Wickramasinghe SA(89)oct;
Rugar & Hansma PT(90)oct;
news pw(04)jun [100-pm resolution];
Stomp et al PRL(05)cm
+ pw(05)jan [electrons, 50 nm resolution];
Eaton & West 10;
Bonson et al AJP(11)feb [working model];
news BBC(11)mar [imaging of single molecule];
Gauthier Phy(19) [3D imaging].
@ Field-emission microscopy: news SA(09)dec [images of electron orbitals].
@ Other types: Cybulski et al PLOS(14)-a1403 [foldscope, an origami-based paper microscope];
Kuhr Phy(19)apr
[subwavelength-resolution imaging techniques for ultracold atoms].
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send feedback and suggestions to bombelli at olemiss.edu – modified 14 may 2019