Abstract
Excitons in crystals may affect the NMR spectra in all cases when hyperfine interaction of the charge carriers forming excitons with the nuclear spins takes place. The modulation of this interaction by the lattice vibrations influences the nuclear spin relaxation rate through the excitons. The local magnetic field of the excitons also shifts the energy of the nuclear spin levels and, correspondingly, the NMR frequencies (the exciton Knight shift). These shifts essentially depend on the type of statistics of the exciton gas. This fact may be used practically for the purpose of diagnostics of the exciton gas. Specifically, the exciton Knight shift exhibits a sharp increase at the phase transition of the exciton gas to the Bose–Einstein condensate state. The influence of excitons on NMR in semiconductors is considered in Sects. 5.1–5.3.
Section 5.4 shows that the nuclear spin relaxation rate is also influenced by orthobiexcitons. The biexciton contribution to the nuclear spin–lattice relaxation rate may be separated from the exciton contribution. The influence of the excitons on the nuclear spin relaxation, in turn, may be separated from the influence of the free carriers. Thus, the free carriers, excitons, and biexcitons may influence the relaxation of nuclear spins differently. This fact may be used in the investigation of these quasi-particles by NMR.
Section 5.5 discusses the experimental narrowing of exciton absorption lines broadened due to intraband exciton–exciton interaction at high levels of optical excitation. This method, consisting in the action of terasound pulses on exciton gas, is similar to the narrowing of NMR lines under the action of the four-pulse sequence known in high-resolution NMR spectroscopy as WAHUHA.
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Notes
- 1.
According to [423], the maximal concentration of excitons in the CuCl crystal at laser excitation may be ∼4⋅1020 cm−3.
References
A. Abragam, The Principles of Nuclear Magnetism (Clarendon Press, Oxford, 1994), 614 pp. Reprint edition
J.S. Waugh, New NMR Methods in Solid State Physics (Mir, Moscow, 1978), 179 pp. [Russian translation]
U. Heberlen, M. Mehring, High Resolution NMR in Solids (Mir, Moscow, 1980), 504 pp. [Russian translation]
R.S. Knox, Theory of Excitons (Mir, Moscow, 1966), 219 pp. [Russian translation]
L.V. Keldysh, Collective properties of excitons in semiconductors, in Excitons in Semiconductors, adv. ed. B.M. Vul (Nauka, Moscow, 1971), pp. 5–18
S.A. Moskalenko, D.W. Snoke, Bose–Einstein Condensation of Excitons and Biexcitons and Coherent Nonlinear Optics with Excitons (Cambridge University Press, Cambridge, 2000), 415 pp.
S.A. Moskalenko, A.I. Bobrysheva, A.V. Lelyakov, M.F. Migleia, P.I. Hadji, M.I. Shmiglyuk, The Interaction of Excitons in Semiconductors (Stiinta, Chisinau, 1974), 211 pp.
A.I. Bobrysheva, Biexcitons in Semiconductors (Stiinta, Chisinau, 1979), 181 pp.
I.I. Geru, Low Frequency Resonance of Excitons and Impurity Centers (Stiinta, Chisinau, 1976), 194 pp.
S.A. Moskalenko, Bose–Einstein Condensation of Excitons and Biexcitons (RIO AN MSSR, Chisinau, 1970), 167 pp.
A.I. Bobrysheva, I.A. Carp, S.A. Moskalenko, Fiz. Tekh. Poluprovodn. 9(3), 605–607 (1975)
N. Nagasawa, N. Nakata, Y. Doi, M. Yeta, J. Phys. Soc. Jpn. 38(2), 593 (1975)
M.G. Matsko, J. Exp. Theor. Phys. 21(5), 281–285 (1975)
I.I. Geru, A.H. Rotaru, Fiz. Tverd. Tela 18(9), 2766–2771 (1976)
J. Schwinger, On angular momentum, in Quantum Theory of the Angular Momentum, ed. by L.C. Biedenharn, H. Van Dam (Academic Press, New York, 1965), pp. 229–279
I.I. Geru, A.H. Rotaru, Fiz. Tverd. Tela 18, 2993–2996 (1976)
I.I. Geru, A.H. Rotaru, Spin–lattice relaxations of nuclei via Wannier–Mott excitons, in Crystalline and Vitreous Semiconductors, ed. by S.I. Radautsan et al. (Stiinta, Chisinau, 1977), pp. 46–53
A.H. Rotaru, I.I. Geru, Spin–lattice relaxation of nuclei via orthobiexcitons, in Crystalline and Vitreous Semiconductors, ed. by S.I. Radautsan et al. (Stiinta, Chisinau, 1977), pp. 53–61
I.I. Geru, A.H. Rotaru, Relaxation of nuclear spin and Knight shift due to the Wannier–Mott excitons, in Abstracts of the XVIIIth Congress AMPERE “Magnetic Resonance and Related Phenomena”, Nottingham, England, 9–14 September (1974), p. 152
V.A. Piragas, Fiz. Tverd. Tela 13(7), 2013–2017 (1971)
P.I. Hadji, Fiz. Tverd. Tela 15(6), 1718–1726 (1973)
A. Bivas, R. Levy, S. Nikitine, J.B. Grun, J. Phys. 31(2–3), 227–234 (1970)
A.P. Prudnikov, Yu.A. Brychkov, O.I. Marichev, Integrals and Series (Nauka, Moscow, 1981), 798 pp.
T. Ugumori, K. Masuda, S. Namba, J. Phys. Soc. Jpn. 41(6), 1991–1995 (1976)
T. Ugumori, K. Masuda, S. Kamba, J. Phys. Soc. Jpn. 43(1), 151–156 (1977)
M.S. Brodin, I.I. Geru, V.P. Karperko, M.G. Matsko, Ukr. Fiz. Zh. 26(5), 867–869 (1981)
A. Balzarotti, M. Grandolfo, F. Somma, P. Vecchia, Phys. Status Solidi (b) 44(2), 713–716 (1971)
M.S. Brodin, V.M. Bandura, I.I. Geru, M.G. Matzko, Fiz. Tverd. Tela 24(10), 3133–3136 (1982)
I.I. Geru, J. Phys., Conf. Ser. 324(1), 012023 (2011). doi:10.1088/1742-6596/324/1/012023
L.L. Buishvili, M.G. Menadbe, J. Exp. Theor. Phys. 77(6), 2435–2442 (1979)
B.P. Provotorov, E.B. Fel’dman, J. Exp. Theor. Phys. 79(6), 2206–2217 (1980)
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Geru, I., Suter, D. (2013). Investigation of Excitons by NMR Spectroscopy Methods. In: Resonance Effects of Excitons and Electrons. Lecture Notes in Physics, vol 869. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-35807-4_5
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