Staff profile

• atomic theory
• multiphoton processes in strong laser fields

Authored book

• Joachain, C., Kylstra, N., & Potvliege, R. (2012). Atoms in Intense Laser Fields. Cambridge University Press

Chapter in book

• Potvliege, R., & Shakeshaft, R. (1992). Nonperturbative Treatment of Multiphoton Ionization Within the Floquet Framework. In M. Gavrila (Ed.), Atoms in Intense Laser Fields (373-433). Academic Press

Conference Paper

• Griffin, P., Weatherill, K., Macleod, S., Potvliege, R., & Adams, C. (2005). Loading of selected sites in an optical lattice using light-shift engineering. In E. Hinds, A. Ferguson, & E. Riis (Eds.), Laser spectroscopy : XVII International Conference of Laser Spectroscopy ; proceedings (307-314). https://doi.org/10.1142/9789812701473_0032
• Joachain, C., Kylstra, N., & Potvliege, R. (2002). Non-dipole and relativistic effects in laser-atom interactions.
• Potvliege, R., & Smith, P. H. (1993). Stabilization of Excited States and Harmonic Generation: Recent Theoretical Results in the Sturmian-Floquet Approach.

Journal Article

• Rotunno, A. P., Berweger, S., Prajapati, N., Simons, M. T., Artusio-Glimpse, A. B., Holloway, C. L., …Adams, C. (2023). Detection of 3–300 MHz electric fields using Floquet sideband gaps by “Rabi matching” dressed Rydberg atoms. Journal of Applied Physics, 134(13), Article 134501. https://doi.org/10.1063/5.0162101
• Robertson, E., Sibalic, N., Potvliege, R., & Jones, M. (2021). ARC 3.0: An expanded Python toolbox for atomic physics calculations. Computer Physics Communications, 261(107814), Article 107814. https://doi.org/10.1016/j.cpc.2020.107814
• Jones, M., Potvliege, R., & Spannowsky, M. (2020). Probing new physics using Rydberg states of atomic hydrogen. Physical Review Research, 2(1), Article 013244. https://doi.org/10.1103/physrevresearch.2.013244
• Ogden, T. P., Whittaker, K., Keaveney, J., Wrathmall, S., Adams, C., & Potvliege, R. (2019). Quasisimultons in Thermal Atomic Vapors. Physical Review Letters, 123(24), Article 243604. https://doi.org/10.1103/physrevlett.123.243604
• Vaillant, C., Potvliege, R., & Jones, M. (2015). Intercombination effects in resonant energy transfer. Physical Review A, 92(4), Article 042705. https://doi.org/10.1103/physreva.92.042705
• Jacobs, V., Burke, P., & Potvliege, R. (2014). Liouville-space R-matrix-Floquet description of atomic radiative processes involving autoionizing states in the presence of intense electromagnetic fields. Journal of Physics B: Atomic, Molecular and Optical Physics, 47(2), Article 025401. https://doi.org/10.1088/0953-4075/47/2/025401
• Vaillant, C., Jones, M., & Potvliege, R. (2014). Multichannel quantum defect theory of strontium bound Rydberg states. Journal of Physics B: Atomic, Molecular and Optical Physics, 47(15), Article 155001. https://doi.org/10.1088/0953-4075/47/15/155001
• Vaillant, C., Jones, M., & Potvliege, R. (2012). Long-range Rydberg–Rydberg interactions in calcium, strontium and ytterbium. Journal of Physics B: Atomic, Molecular and Optical Physics, 45(13), Article 135004. https://doi.org/10.1088/0953-4075/45/13/135004
• Millen, J., Lochead, G., Corbett, G., Potvliege, R., & Jones, M. (2011). Spectroscopy of a cold strontium Rydberg gas. Journal of Physics B: Atomic, Molecular and Optical Physics, 44(18), Article 184001. https://doi.org/10.1088/0953-4075/44/18/184001
• Tanasittikosol, M., Pritchard, J., Maxwell, D., Gauguet, A., Weatherill, K., Potvliege, R., & Adams, C. (2011). Microwave dressing of Rydberg dark states. Journal of Physics B: Atomic, Molecular and Optical Physics, 44(18), Article 184020. https://doi.org/10.1088/0953-4075/44/18/184020
• Bason, M., Tanasittikosol, M., Sargsyan, A., Mohapatra, A., Sarkisyan, D., Potvliege, R., & Adams, C. (2010). Enhanced electric field sensitivity of rf-dressed Rydberg dark states. New Journal of Physics, 12, Article 065015. https://doi.org/10.1088/1367-2630/12/6/065015
• Potvliege, R., Mese, E., & Vucic, S. (2010). Multiphoton ionization and multiphoton resonances in the tunneling regime. Physical Review A, 81(5), Article 053402. https://doi.org/10.1103/physreva.81.053402
• Potvliege, R., & Vucic, S. (2009). Freeman resonances in high-order above-threshold ionization. Journal of Physics B: Atomic, Molecular and Optical Physics, 42(5), Article 055603. https://doi.org/10.1088/0953-4075/42/5/055603
• Meṣe, E., & Potvliege, R. (2008). Quasienergy spectrum of complex atoms. Physical Review A, 77(2), Article 023414. https://doi.org/10.1103/physreva.77.023414
• Krajewska, K., Kaminski, J., & Potvliege, R. (2008). Long-lived resonances supported by a contact interaction in crossed magnetic and electric fields. Annals of Physics, 323, 2639-2653. https://doi.org/10.1016/j.aop.2008.02.006
• Mese, E., & Potvliege, R. (2007). The quasienergy spectrum of argon from 400 to 800 nm. Laser Physics Letters, 4(5), 357-362
• Potvliege, R., & Vucic, S. (2006). Stark-shift induced resonances in multiphoton ionization. Physica Scripta, 74(4), C55-C60
• Potvliege, R., & Adams, C. (2006). Photo-ionization in far-off-resonance optical lattices. New Journal of Physics, 8,
• Potvliege, R., & Vucic, S. (2006). High-order above-threshold ionization of argon: plateau resonances and the Floquet quasienergy spectrum. Physical Review A, 74(2), https://doi.org/10.1103/physreva.74.023412
• Griffin, P., Weatherill, K., MacLeod, S., Potvliege, R., & Adams, C. (2006). Spatially selective loading of an optical lattice by light-shift engineering using an auxiliary laser field. New Journal of Physics, 8(11), https://doi.org/10.1088/1367-2630/8/1/011
• Mese, E., & Potvliege, R. (2006). Ellipticity dependence of harmonic generation in atomic hydrogen. Journal of Physics B: Atomic, Molecular and Optical Physics, 39(2), 431-442
• Chirilă, C., & Potvliege, R. (2005). Low-order above-threshold ionization in intense few-cycle laser pulses. Physical Review A, 71(2), https://doi.org/10.1103/physreva.71.021402
• Krajewska, K., Kaminski, J., & Potvliege, R. (2005). Stabilization Of Resonance States In Crossed Magnetic And Laser Fields In A Parabolic Quantum Well. Laser Physics, 15, 238-244
• Chirilă, C., Joachain, C., Kylstra, N., & Potvliege, R. (2004). Interaction of superintense laser pulses with relativistic ions. Physical Review Letters, 93(24), https://doi.org/10.1103/physrevlett.93.243603
• Chirila, C., Joachain, C., Kylstra, N., & Potvliege, R. (2004). Three-step Processes With Relativistic Ions. Laser Physics, 14, 190-193
• Joachain, C., Kylstra, N., & Potvliege, R. (2003). Atoms in intense, ultrashort laser pulses: non-dipole and relativistic effects. Journal of Modern Optics, 50, 313-329
• Potvliege, R. (2003). Light-Induced States of Atoms in Intense Laser Fields. Physica Scripta, 68, 18-. https://doi.org/10.1238/physica.regular.068ac0018
• Chirilă, C., Kylstra, N., Potvliege, R., & Joachain, C. (2002). Nondipole effects in photon emission by laser-driven ions. Physical Review A, 66(6), https://doi.org/10.1103/physreva.66.063411
• Garland, L., Jaron, A., Kaminski, J., & Potvliege, R. (2002). Off-shell effects in laser-assisted electron scattering at low frequency. Journal of Physics B: Atomic, Molecular and Optical Physics, 35(13), 2861-2872. https://doi.org/10.1088/0953-4075/35/13/302
• Kylstra, N., Potvliege, R., & Joachain, C. (2002). Photon Emission By Ions Interacting With Short Intense Laser Pulses. Laser Physics, 12, 409-414
• Dorr, M., Kylstra, N., & Potvliege, R. (2001). Photoionization By Ultrashort Pulses In The High-intensity Limit. Laser Physics, 11, 250-254
• Bauer, J., Plucinski, L., Piraux, B., Potvliege, R., Gajda, M., & Krzywinski, J. (2001). Ionization of hydrogen atoms by intense vacuum ultraviolet radiation. Journal of Physics B: Atomic, Molecular and Optical Physics, 34, 2245-2254
• Kylstra, N., Potvliege, R., & Joachain, C. (2001). LETTER TO THE EDITOR: Photon emission by ions interacting with short intense laser pulses: beyond the dipole approximation. Journal of Physics B: Atomic, Molecular and Optical Physics, 34, L55-L61. https://doi.org/10.1088/0953-4075/34/3/101
• Potvliege, R., & Zehnlé, V. (2001). Complex scaling calculation of the decaying quantum-propagation modes of neutral atoms in a magnetic guide. Physical Review A, 63, 025601-
• Day, H., Piraux, B., & Potvliege, R. (2000). Multistate non-Hermitian Floquet dynamics in short laser pulses. Physical Review A, 61, 031402-
• Potvliege, R. (2000). Waveletlike Basis Function Approach To The Propagation Of Paraxial Beams. Journal of the Optical Society of America. A, Optics and image science, 17, 1043-1047. https://doi.org/10.1364/josaa.17.001043
• Potvliege, R., Kylstra, N., & Joachain, C. (2000). LETTER TO THE EDITOR: Photon emission by He⁺ in intense ultrashort laser pulses. Journal of Physics B: Atomic, Molecular and Optical Physics, 33, L743-L748. https://doi.org/10.1088/0953-4075/33/20/10d
• Potvliege, R. (2000). Disappearance of the dressed bound states in photodetachment from a short-range potential by an intense high-frequency laser field. Physical Review A, 62, 013403-
• Jaron, A., Mese, E., & Potvliege, R. (2000). Floquet analysis of laser-induced continuum structures. Journal of Physics B: Atomic, Molecular and Optical Physics, 33, 1487-1505. https://doi.org/10.1088/0953-4075/33/8/302
• Potvliege, R. (2000). Role Of The Magnetic Component Of The Incident Field In The Adiabatic Stabilization Of Circular States. Laser Physics, 10, 143-146
• Caron, C., & Potvliege, R. (2000). propBG: A program for calculating the intensity and the far-field profile of harmonics emitted by a dilute gas irradiated by an intense Gaussian or Bessel-Gauss laser beam. Computer Physics Communications, 126, 269-293
• Dörr, M., & Potvliege, R. (2000). LETTER TO THE EDITOR: Adiabatic stabilization in photodetachment by ultrashort pulses. Journal of Physics B: Atomic, Molecular and Optical Physics, 33, L233-L238. https://doi.org/10.1088/0953-4075/33/6/107
• Caron, C., & Potvliege, R. (2000). Free-space propagation of ultrashort pulses: space-time couplings in Gaussian pulse beams. Journal of Modern Optics, 46, 1881-1891
• Potvliege, R. (1999). A Program For Time-independent Calculations Of Multiphoton Processes In One-electron Atomic Systems. Laser Physics, 9, 413-415
• Potvliege, R. (1999). Adiabatic stabilization in a two-color field. Physical Review A, 60, 1311-1313
• Caron, C., & Potvliege, R. (1999). Optimum conical angle of a BesselGauss beam for low-order harmonic generation in gases. Journal of the Optical Society of America B, 16, 1377-1384
• Caron, C., & Potvliege, R. (1999). Bessel-modulated Gaussian beams with quadratic radial dependence. Optics Communications, 164, 83-93
• Piraux, B., & Potvliege, R. (1998). Adiabatic stabilization of a circular state: Theory compared to experiment. Physical Review A, 57, 5009-5012
• Potvliege, R. (1998). STRFLO: a program for time-independent calculations of multiphoton processes in one-electron atomic systems I. Quasienergy spectra and angular distributions. Computer Physics Communications, 114, 42-93. https://doi.org/10.1016/s0010-4655%2898%2900073-3
• Caron, C., & Potvliege, R. (1998). Phase matching and harmonic generation in Bessel Gauss beams. Journal of the Optical Society of America B, 15, 1096-1106
• Day, H., Fearnside, A., & Potvliege, R. (1997). Shifted channel wave numbers in approximate Floquet calculations. Physical Review A, 56, 2447-2450. https://doi.org/10.1103/physreva.56.2447
• Fearnside, A., Potvliege, R., & Shakeshaft, R. (1995). Light-induced states of H and H⁻, shadow states, and the dressed potential. Physical Review A, 51, 1471-1481. https://doi.org/10.1103/physreva.51.1471
• Dörr, M., Joachain, C., Potvliege, R., & VučiĆ, S. (1994). Born-Floquet theory of laser-assisted electron-atom collisions. Physical Review A, 49, 4852-4863. https://doi.org/10.1103/physreva.49.4852
• Potvliege, R., & Smith, P. H. (1994). Two-color ionization of hydrogen for frequencies in the 2:3 ratio. Physical Review A, 49, 3110-3113
• Rottke, H., Wolff-Rottke, B., Feldmann, D., Welge, K., Dörr, M., Potvliege, R., & Shakeshaft, R. (1994). Atomic hydrogen in a strong optical radiation field. Physical Review A, 49, 4837-4851. https://doi.org/10.1103/physreva.49.4837
• Dorr, M., Joachain, C., Potvliege, R., & Vucic, S. (1994). Born-floquet Theory Of Electron-atom Collisions In The Presence Of A Laser Field. Zeitschrift für Physik. D, Atoms, molecules and clusters, 29, 245-246. https://doi.org/10.1007/bf01437841
• Potvliege, R., & Smith, P. H. (1993). Adiabatic stabilization of excited states of H in an intense linearly polarized laser field. Physical Review A, 48, 46-
• Pont, M., Potvliege, R., Shakeshaft, R., & Smith, P. H. (1992). Geometric phases in multiphoton ionization. Physical Review A, 46, 555-566
• Madajczyk, J., Pont, M., Potvliege, R., Shakeshaft, R., & Taylor, H. (1992). Photoionization of atomic hydrogen dressed by a circularly polarized CO2-laser field. Physical Review A, 45, 4848-4854. https://doi.org/10.1103/physreva.45.4848
• Dörr, M., Potvliege, R., Proulx, D., & Shakeshaft, R. (1992). Erratum: Multiphoton processes in an intense laser field. VI. Two-color ionization with incommensurable frequencies [Phys. Rev. A 44, 574 (1991)]. Physical Review A, 45, 2142-
• Potvliege, R., & Smith, P. (1992). Two-colour multiphoton ionization of hydrogen by an intense laser field and one of its harmonics. Journal of Physics B: Atomic, Molecular and Optical Physics, 25, 2501-2516. https://doi.org/10.1088/0953-4075/25/11/007
• Dörr, M., Feldmann, D., Potvliege, R., Rottke, H., Shakeshaft, R., Welge, K., & Wolff-Rottke, B. (1992). The energy spectrum of photoelectrons produced by multiphoton ionization of atomic hydrogen. Journal of Physics B: Atomic, Molecular and Optical Physics, 25, L275-L280. https://doi.org/10.1088/0953-4075/25/12/001
• Pont, M., Potvliege, R., Shakeshaft, R., & Teng, Z. (1992). Low-frequency theory of multiphoton ionization. II. General formulation and further results for ionization of H(1s). Physical Review A, 45, 8235-8251. https://doi.org/10.1103/physreva.45.8235
• Potvliege, R., & Smith, P. (1991). Two-colour multiphoton ionization of hydrogen by an intense laser field and its third harmonic. Journal of Physics B: Atomic, Molecular and Optical Physics, 24, L641-L646. https://doi.org/10.1088/0953-4075/24/24/001
• Taieb, R., Veniard, V., Maquet, A., Vucic, S., & Potvliege, R. (1991). Light polarization effects in laser-assisted (e, 2e) collisions: a Sturmian approach. Journal of Physics B: Atomic, Molecular and Optical Physics, 24, 3229-3240. https://doi.org/10.1088/0953-4075/24/14/016
• Dörr, M., Potvliege, R., Proulx, D., & Shakeshaft, R. (1991). Multiphoton processes in an intense laser field. V. The high-frequency regime. Physical Review A, 43, 3729-3740
• Dörr, M., Potvliege, R., Proulx, D., & Shakeshaft, R. (1991). Multiphoton processes in an intense laser field. VI. Two-color ionization with incommensurable frequencies. Physical Review A, 44, 574-583. https://doi.org/10.1103/physreva.44.574
• Potvliege, R., & Shakeshaft, R. (1990). Multiphoton processes in an intense laser field. II. Partial rates and angular distributions for ionization of atomic hydrogen at 532 nm. Physical Review A, 41, 1609-1619. https://doi.org/10.1103/physreva.41.1609
• Dörr, M., Potvliege, R., Proulx, D., & Shakeshaft, R. (1990). Multiphoton detachment of H⁻ and the applicability of the Keldysh approximation. Physical Review A, 42, 4138-4150. https://doi.org/10.1103/physreva.42.4138
• Shakeshaft, R., Potvliege, R., Dörr, M., & Cooke, W. (1990). Multiphoton processes in an intense laser field. IV. The static-field limit. Physical Review A, 42, 1656-1668. https://doi.org/10.1103/physreva.42.1656
• Dörr, M., Potvliege, R., & Shakeshaft, R. (1990). Atomic hydrogen irradiated by a strong laser field: Sturmian basis calculations of rates for high-order multiphoton ionization, Raman scattering, and harmonic generation. Journal of the Optical Society of America B, 7, 433-448
• Dörr, M., Potvliege, R., & Shakeshaft, R. (1990). Tunneling ionization of atomic hydrogen by an intense low-frequency field. Physical Review Letters, 64, 2003-2006
• Dörr, M., Potvliege, R., & Shakeshaft, R. (1990). Multiphoton processes in an intense laser field: III. Resonant ionization of hydrogen by subpicosecond pulses. Physical Review A, 41, 558-561. https://doi.org/10.1103/physreva.41.558
• Dörr, M., & Potvliege, R. (1990). Resonances that originate from shadow poles of the scattering matrix in multiphoton processes. Physical Review A, 41, 1472-1476. https://doi.org/10.1103/physreva.41.1472
• Potvliege, R., & Joachain, C. (1990). State multipoles for the excitation of the n=2 manifold of atomic hydrogen by fast electrons and positrons. Journal of Physics B: Atomic, Molecular and Optical Physics, 23, 841-851. https://doi.org/10.1088/0953-4075/23/5/009
• Pont, M., Shakeshaft, R., & Potvliege, R. (1990). Low-frequency theory of multiphoton ionization. Physical Review A, 42, 6969-6972
• Potvliege, R., & Shakeshaft, R. (1989). High-order Harmonic-generation And Raman-scattering By Hydrogen In Perturbation-theory. Zeitschrift für Physik. D, Atoms, molecules and clusters, 11, 93-94. https://doi.org/10.1007/bf01436589
• Vucic, S., Potvliege, R., & Joachain, C. (1989). Second Born triple differential cross sections for the coplanar asymmetric ionisation of He(2¹S) and He(2³S) by fast electrons and positrons. Journal of Physics B: Atomic, Molecular and Optical Physics, 22, 3519-3527. https://doi.org/10.1088/0953-4075/22/21/014
• Potvliege, R., & Shakeshaft, R. (1989). High-order above-threshold ionization of hydrogen in perturbation theory. Physical Review A, 39, 1545-1548
• Potvliege, R. (1989). The structure of the Glauber third-order optical potential. Journal of Physics B: Atomic, Molecular and Optical Physics, 22, 907-912. https://doi.org/10.1088/0953-4075/22/6/016
• Potvliege, R., & Shakeshaft, R. (1989). Multiphoton processes in an intense laser field: Harmonic generation and total ionization rates for atomic hydrogen. Physical review. A, General physics, 40, 3061-3079. https://doi.org/10.1103/physreva.40.3061
• Vucic, S., Potvliege, R., & Joachain, C. (1988). CORRIGENDUM: Third-order optical model analysis of e+/-H(2s), e+/-He(2¹S) and e+/-He(2³S) elastic scattering at intermediate energies. Journal of Physics B: Atomic, Molecular and Optical Physics, 21, 2801-
• Potvliege, R., & Shakeshaft, R. (1988). Determination of the scattering matrix by use of the Sturmian representation of the wavefunction: choice of basis wavenumber. Journal of Physics B: Atomic, Molecular and Optical Physics, 21, L645-L650. https://doi.org/10.1088/0953-4075/21/21/001
• Potvliege, R., & Shakeshaft, R. (1988). Nonperturbative calculation of partial differential rates for multiphoton ionization of a hydrogen atom in a strong laser field. Physical review. A, General physics, 38, 1098-1100. https://doi.org/10.1103/physreva.38.1098
• Potvliege, R., & Shakeshaft, R. (1988). Time-independent theory of multiphoton ionization of an atom by an intense field. Physical review. A, General physics, 38, 4597-4621. https://doi.org/10.1103/physreva.38.4597
• Joachain, C., & Potvliege, R. (1988). Differential cross sections for positron-atomic-hydrogen inelastic scattering at intermediate energies. Physical review. A, General physics, 38, 4337-4339. https://doi.org/10.1103/physreva.38.4337
• Potvliege, R., & Shakeshaft, R. (1988). Movement and interplay of the bound state, resonance, and shadow poles of the scattering amplitude in multiphoton processes. Physical review. A, General physics, 38, 6190-6203. https://doi.org/10.1103/physreva.38.6190
• Potvliege, R., Furtado, F., & Joachain, C. (1987). Multichannel optical mole theory of proton-hydrogen and proton-helium elastic scattering at intermediate energies. Journal of physics. B. Atomic and molecular physics, 20, 1771-1787. https://doi.org/10.1088/0022-3700/20/8/014
• Shakeshaft, R., & Potvliege, R. (1987). Approximate theory for multiphoton ionization of an atom by an intense field. Physical Review A, 36, 5478-5481
• Vuić, S., Potvliege, R., & Joachain, C. (1987). Second Born triple-differential cross sections for the coplanar asymmetric ionization of H(2s) by fast electrons. Physical review. A, General physics, 35, 1446-1449. https://doi.org/10.1103/physreva.35.1446
• Joachain, C., & Potvliege, R. (1987). Importance of absorption effects on fast positron-argon differential cross sections. Physical review. A, General physics, 35, 4873-4875. https://doi.org/10.1103/physreva.35.4873
• Vucic, S., Potvliege, R., & Joachain, C. (1987). Third-order optical model analysis of e+or-H(2s), e+or-He(2¹S) and e+or-He(2³S) elastic scattering at intermediate energies. Journal of Physics B: Atomic, Molecular and Optical Physics, 20, 3157-3169
• Byron, F., Jr., J., C.j., P., & M., R. (1985). Elastic and inelastic scattering of electrons and positrons by atomic hydrogen at intermediate and high energies in the unitarised eikonal-Born series method. Journal of physics. B. Atomic and molecular physics, 18, 1637-1660. https://doi.org/10.1088/0022-3700/18/8/018
• Joachain, C., Piraux, B., Potvliege, R., Furtado, F., & Byron, F. (1985). Unitarised eikonal-Born series theory of (e, 2e) reactions in atomic hydrogen. Physics Letters A, 112, 138-140. https://doi.org/10.1016/0375-9601%2885%2990674-7
• Potvliege, R., & Joachain, C. (1985). Coherent electron impact excitation of the n=2 states of atomic hydrogen at intermediate energies. Journal of physics. B. Atomic and molecular physics, 18, L585-L588. https://doi.org/10.1088/0022-3700/18/16/009
• McDowell, M., Edmunds, P., Potvliege, R., Joachain, C., Shingal, R., & Bransden, B. (1984). The angular distribution of asymmetry in scattering of spin-polarised electrons by spin-polarised hydrogen atoms. II. Journal of physics. B. Atomic and molecular physics, 17, 3951-3963. https://doi.org/10.1088/0022-3700/17/19/017
• Byron, F., Jr., J., C.j., P., & M., R. (1982). Unitarisation of the eikonal-Born series method for electron-atom and positron-atom collisions. Journal of physics. B. Atomic and molecular physics, 15, 3915-3943. https://doi.org/10.1088/0022-3700/15/21/014
• Byron, F., Jr., J., C.j., P., & M., R. (1981). Unitarisation of the eikonal-Born series method for electron- and positron-atom collisions. Journal of physics. B. Atomic and molecular physics, 14, L609-L615. https://doi.org/10.1088/0022-3700/14/19/005