handbook of carbon, graphite, diamond and fullerenes

6.3 Luminescence
Structure and Properties of Diamond 267
Visible luminescence is a well-known optical property of single crystal
diamond particularly in the blue and green regions. This luminescence
originates in the states at mid-bandgap and is caused by impurities and
lattice defects. Cathodoluminescence (CL) is another characteristic of
diamond. The CL of single crystal diamond is described as a band-A
luminescence and the peak of the spectra is found between 2.4 and 2.8 eV
(from green to purple-blue).t 12 N 18 H 19 ]
6.4 Index of Refraction
The index of refraction of diamond is high as shown in Table 11.5 and
only afew materials have higher indices (Si: 3.5, rutile: 2.9, AIC3:2.7, Cu2O:
2.7). All ionic crystals have lower indices.
Table 11.5. Index of Refraction of Diamond and Selected Materials
Material
Diamond
Quartz
Crown glass
Air
Index
2.4237
2.4099
2.41726
2.43554
2.7151
1.456
1.574
1.539
1.497
I.000
* Near cut-off in the ultraviolet
Wavelength
(nm)
546.1 (Hg green)
656.28 (C-line)
589.29 (D-line)
486.13 (F-line)
226.5 *
0.656
0.185
0.361
2
0.589