flourescent dyes. Several exploratory devices, whose characteristics are changeable
by varying the constituent nanocrystal diameter, have been made. While isolated
nanocrystals are interesting by themselves, their organizations, of especially those
which are capable of self-assembling into well-ordered arrays, have attracted greater
attention. Nanocrystals anchored to fragments of DNA or similar molecules essentially form one-dimensional organizations. When coated with long-chain alkane
thiols, nanocrystals exhibit a tendency to assemble into hexagonal arrays on flat
substrates. The stability of such a two-dimensional organization depends on the
diameter of the nanocrystals and the length of the ligand. Multilayers of nanocrystal arrays can also be made in a programmed way by selecting suitable spacer
molecules. However, patterns of nanocrystals can be obtained using scanning
probe techniques. Another mesoscalar aggregation known is the giant clusters
of nanocrystals with definite nuclearities. It would be ideal to grow crystals of
nanocrystals, but such efforts have met with only a limited success to date, giving
micron-sized crystals. Nanocrystal organizations may exhibit properties very different from those of the individual nanocrystal. They are amenable to unprecedented control over the lattice, the size of the nanocrystal and the interparticle
separation, being continuously variable over a range. Exploratory experiments for
measuring such collective properties are currently underway in several laboratories
around the globe.
References
1 M. Faraday, Philos. Trans. R. Soc.
London, 147, 145, 1857.
2 C. R. Berry, Phys. Rev., 161, 848, 1967.
3 L. E. Brus, J. Chem. Phys., 80, 4403,
1984.
4 C. N. R. Rao, G. U. Kulkarni, P. J.
Thomas et al., Chem. Eur. J., 29, 27,
2002.
5 P. P. Edwards, R. L. Johnston, C. N.
R. Rao, in Metal Clusters in Chemistry,
ed. P. Braunstein, G. Oro, P. R.
Raithby, Wiley-VCH, Weinheim 1999.
6 S. Link, M. A. El-Sayed, J. Phys.
Chem. B, 105, 1, 2001.
7 S. Link, M. A. El-Sayed, Int. Rev.
Phys. Chem., 19, 409, 2001.
8 P. Mulvaney, Langmuir, 12, 788, 1996.
9 G. Mie, Ann. Phys., 25, 377, 1908.
10 G. C. Papavassilliou, Prog. Solid State
Chem., 12, 185, 1980.
11 R. Gans, Ann. Phys., 31, 881, 1911.
12 R. Gans, Ann. Phys., 47, 270, 1915.
13 A. C. Templeton, J. J. Pietron, R. W.
Murray et al., J. Phys. Chem. B, 104,
564, 2000.
14 S. V. Gaponenko, Optical Properties of
Semiconductor Nanocrystals, Cambridge
University Press, Cambridge 1998.
15 T. Vossmeyer, L. Katsikas, M.
Giersig et al., J. Phys. Chem., 98,
7665, 1994.
16 C. B. Murray, S. Sun, W. Gaschler
et al., IBM J. Res. Dev., 45, 47, 2001.
17 O. I. Micic, K. M. Jones, A. Cahill et
al., J. Phys. Chem. B, 102, 9791, 1998.
18 L. E. Brus, J. Chem. Phys., 79, 5566,
1983.
19 L. E. Brus, J. Chem. Phys., 80, 4403,
1984.
20 P. E. Lippens, M. Lannoo, Phys. Rev.
B, 39, 10935, 1989.
21 M. V. R. Krishna, R. A. Friesner, J.
Chem. Phys., 95, 8309, 1991.
22 S. Sapra, N. Shanthi, D. D. Sharma,
Phys. Rev. B, 66, 205202, 2002.
23 L. Manna, E. C. Scher, A. P.
Alivisatos, J. Am. Chem. Soc., 122,
12700, 2000.
24 T. Trindade, P. O’Brien, N. L.
Pickett, Chem. Mater., 13, 3843, 2001.
4 Mesoscopic Assembly and Other Properties of Metal and Semiconductor Nanocrystals
88
by varying the constituent nanocrystal diameter, have been made. While isolated
nanocrystals are interesting by themselves, their organizations, of especially those
which are capable of self-assembling into well-ordered arrays, have attracted greater
attention. Nanocrystals anchored to fragments of DNA or similar molecules essentially form one-dimensional organizations. When coated with long-chain alkane
thiols, nanocrystals exhibit a tendency to assemble into hexagonal arrays on flat
substrates. The stability of such a two-dimensional organization depends on the
diameter of the nanocrystals and the length of the ligand. Multilayers of nanocrystal arrays can also be made in a programmed way by selecting suitable spacer
molecules. However, patterns of nanocrystals can be obtained using scanning
probe techniques. Another mesoscalar aggregation known is the giant clusters
of nanocrystals with definite nuclearities. It would be ideal to grow crystals of
nanocrystals, but such efforts have met with only a limited success to date, giving
micron-sized crystals. Nanocrystal organizations may exhibit properties very different from those of the individual nanocrystal. They are amenable to unprecedented control over the lattice, the size of the nanocrystal and the interparticle
separation, being continuously variable over a range. Exploratory experiments for
measuring such collective properties are currently underway in several laboratories
around the globe.
References
1 M. Faraday, Philos. Trans. R. Soc.
London, 147, 145, 1857.
2 C. R. Berry, Phys. Rev., 161, 848, 1967.
3 L. E. Brus, J. Chem. Phys., 80, 4403,
1984.
4 C. N. R. Rao, G. U. Kulkarni, P. J.
Thomas et al., Chem. Eur. J., 29, 27,
2002.
5 P. P. Edwards, R. L. Johnston, C. N.
R. Rao, in Metal Clusters in Chemistry,
ed. P. Braunstein, G. Oro, P. R.
Raithby, Wiley-VCH, Weinheim 1999.
6 S. Link, M. A. El-Sayed, J. Phys.
Chem. B, 105, 1, 2001.
7 S. Link, M. A. El-Sayed, Int. Rev.
Phys. Chem., 19, 409, 2001.
8 P. Mulvaney, Langmuir, 12, 788, 1996.
9 G. Mie, Ann. Phys., 25, 377, 1908.
10 G. C. Papavassilliou, Prog. Solid State
Chem., 12, 185, 1980.
11 R. Gans, Ann. Phys., 31, 881, 1911.
12 R. Gans, Ann. Phys., 47, 270, 1915.
13 A. C. Templeton, J. J. Pietron, R. W.
Murray et al., J. Phys. Chem. B, 104,
564, 2000.
14 S. V. Gaponenko, Optical Properties of
Semiconductor Nanocrystals, Cambridge
University Press, Cambridge 1998.
15 T. Vossmeyer, L. Katsikas, M.
Giersig et al., J. Phys. Chem., 98,
7665, 1994.
16 C. B. Murray, S. Sun, W. Gaschler
et al., IBM J. Res. Dev., 45, 47, 2001.
17 O. I. Micic, K. M. Jones, A. Cahill et
al., J. Phys. Chem. B, 102, 9791, 1998.
18 L. E. Brus, J. Chem. Phys., 79, 5566,
1983.
19 L. E. Brus, J. Chem. Phys., 80, 4403,
1984.
20 P. E. Lippens, M. Lannoo, Phys. Rev.
B, 39, 10935, 1989.
21 M. V. R. Krishna, R. A. Friesner, J.
Chem. Phys., 95, 8309, 1991.
22 S. Sapra, N. Shanthi, D. D. Sharma,
Phys. Rev. B, 66, 205202, 2002.
23 L. Manna, E. C. Scher, A. P.
Alivisatos, J. Am. Chem. Soc., 122,
12700, 2000.
24 T. Trindade, P. O’Brien, N. L.
Pickett, Chem. Mater., 13, 3843, 2001.
4 Mesoscopic Assembly and Other Properties of Metal and Semiconductor Nanocrystals
88