Michael Reid | University of Canterbury/Te Whare Wānanga o Waitaha (original) (raw)
Papers by Michael Reid
Using high-performance computing techniques and targeted experimental investigation we have devel... more Using high-performance computing techniques and targeted experimental investigation we have developed a predictive crystal-field model of the complex hyperfine structure of 167 Er 3+ :Y2SiO5. We simultaneously match site-selective spectroscopic data up to 20,000 cm −1 , rotational Zeeman data, and ground-and excited-state hyperfine structure determined from high-resolution Ramanheterodyne spectroscopy on the 1.5 µm telecom transition. We achieve agreement of better than 50 MHz for assigned hyperfine transitions. The successful analysis of the complex hyperfine patterns opens the possibility of systematically searching this whole class of materials for the ZEFOZ transitions that have proved so useful in quantum information applications.
Physical Review B, 2021
We report on the development and application of a parametrized crystal-field model for both C1 sy... more We report on the development and application of a parametrized crystal-field model for both C1 symmetry centers in trivalent erbium-doped Y2SiO5. High resolution Zeeman and temperature dependent absorption spectroscopy was performed to acquire the necessary experimental data. The obtained data, in addition to the ground (4 I 15/2 Z1) state and exited (4 I 13/2 Y1) state Zeeman and hyperfine structure, was simultaneously fitted in order to refine an existing crystal-field interpretation of the Er 3+ :Y2SiO5 system. We demonstrate that it is possible to account for the electronic, magnetic and hyperfine structure of the full 4f 11 configuration of Er 3+ :Y2SiO5 and further, that it is possible to predict both optical polarization behavior and high magnetic field hyperfine structure of transitions in the 1.5 µm telecommunications band.
Physical Review B, 2021
High-resolution Zeeman spectroscopy of electronic-nuclear hyperfine levels of 5 I8 → 5 I7 transit... more High-resolution Zeeman spectroscopy of electronic-nuclear hyperfine levels of 5 I8 → 5 I7 transitions in Ho 3+ :Y2SiO5 is reported. Crystal-field parameters determined for the two C1 symmetry sites in Er 3+ :Y2SiO5 are successfully used to model the Zeeman-hyperfine data, including the prediction of avoided crossings between hyperfine levels under the influence of an external magnetic field. The two six-and seven-coordinate substitutional sites may be distinguished by comparing the spectra with crystal-field calculations.
Журнал технической физики, 2019
Zeeman spectroscopy is used to demonstrate that phenomenological crystal-field parameters determi... more Zeeman spectroscopy is used to demonstrate that phenomenological crystal-field parameters determined for the two C _1 point-group symmetry sites in Er^3+:Y_2SiO_5 may be transferred to other ions. The two crystallographic six-and seven-coordinate substitutional sites may be distinguished by comparing the spectra with crystal-field calculations.
Journal of Physics: Condensed Matter, 2018
We present a comprehensive spectroscopic study of C 2v point-group symmetry sites in Sm 3+ :CaF 2... more We present a comprehensive spectroscopic study of C 2v point-group symmetry sites in Sm 3+ :CaF 2 /SrF 2 codoped with either NaF or LiF. Data includes electron paramagnetic resonance measurements of Zeeman and hyperfine interactions for the ground state, as well as site-selective excitation and fluorescence spectroscopy up to the 4 G 5/2 multiplet. Inclusion of the EPR data allowed us to determine unique crystalfield parameters. The parameters provide information about the geometry of the sites and the nature of the interactions between the Sm 3+ dopant and the alkaline earth co-dopant.
Physics Letters A, 2005
For emitters embedded in media of various refractive indices, different macroscopic or microscopi... more For emitters embedded in media of various refractive indices, different macroscopic or microscopic theoretical models predict different dependencies of the spontaneous emission lifetime on refractive index. Among those models are the two most promising models: the virtual-cavity model and the real-cavity model. It is a priori not clear which model is more relevant for a given situation. By close analysis of the available experimental results and examining the assumptions underlying the two models, we reach a consistent interpretation of the experimental results and give the criteria which model should apply for a given situation.
The 4 f n →4 f nϪ1 5d(f d) excitation spectra of the heavy lanthanides (Tb 3ϩ , Dy 3ϩ , Ho 3ϩ , E... more The 4 f n →4 f nϪ1 5d(f d) excitation spectra of the heavy lanthanides (Tb 3ϩ , Dy 3ϩ , Ho 3ϩ , Er 3ϩ , Tm 3ϩ , and Yb 3ϩ) incorporated in LiYF 4 , CaF 2 , and YPO 4 are investigated in the ultraviolet and vacuum-ultraviolet spectral region ͑100-275 nm͒. Spin-forbidden transitions as well as spin-allowed transitions are observed for all heavy lanthanides. In the excitation spectra the crystal-field splitting of the 5d electron can be clearly observed. Fine structure ͑zero-phonon lines and vibronic lines͒ is observed for the transition to the lowest 5d crystal-field component, for both the high-spin and low-spin fd bands. Energy-level and intensity calculations are performed by an extension of the commonly used model for energy-level calculations of 4 f n states. A good agreement between experimental and simulated spectra is obtained, using parameters that describe the 5d crystal-field splitting ͑from the spectra of Ce 3ϩ), the parameters for the splitting of the 4 f nϪ1 core ͑from the literature on energy-level calculations for 4 f n states͒ and parameters for the spin-orbit coupling of the 5d electron and the Coulomb interaction between 4 f and 5d electrons ͑from atomic ab initio calculations using the computer code of Cowan͒. To improve the agreement between the model and experiment, the 5d crystalfield parameters were adjusted slightly to correct for the decreasing crystal-field strength for the heavier rare earths due to the lanthanide contraction. The f-d interaction parameters in the fluoride host lattices were reduced to about 67% of the calculated free-ion values in order to compensate for the nephelauxetic effect.
Physical Review Letters, 1993
Burdick and Reid Reply: In our Letter [1] we emphasized the advantages of a many-body perturbatio... more Burdick and Reid Reply: In our Letter [1] we emphasized the advantages of a many-body perturbation theory (MBPT) formalism [2] for transition intensity calcula-(8)
The Journal of Physical Chemistry B, 2006
Detailed analysis of the vibronic structure in the electronic absorption spectrum of Cs 2 NaYbF 6... more Detailed analysis of the vibronic structure in the electronic absorption spectrum of Cs 2 NaYbF 6 at temperatures between 10 and 300 K enables the crystal field energy level diagram of Yb 3+ in this cubic host to be deduced. Ultraviolet and visible laser excitation of Cs 2 NaYbF 6 , Cs 2 NaY 0.9 Yb 0.1 F 6 , and Cs 2 NaHo 0.99 Yb 0.01 F 6 give spectral features mainly due to Yb 3+ being situated at a range of defect sites. The 4f 13 crystal field analyses of octahedral YbX 6 3-(X) F, Cl, Br) systems show the expected trends in parameter values, but the energy level fits are poor. Inclusion of the interaction with the charge-transfer configuration 4f 14 np 5 provides an exact fitting of energy levels for YbX 6 3-, and a smooth variation of ff and fp crystal field parameters for Cs 2 NaLnCl 6 (Ln) Er, Tm, Yb) is observed.
Physical Review Letters, 2002
High-energy transitions in the 4f N ! 4f N21 5d excitation spectra of lanthanide ions in host cry... more High-energy transitions in the 4f N ! 4f N21 5d excitation spectra of lanthanide ions in host crystals are usually broadened due to the short excited-state lifetimes, whereas low-energy transitions, with longer excited-state lifetimes, may show fine structure. We report the surprising observation that for some materials fine structure is observed not only for the low-energy excitation bands but also for some highenergy transitions. The excited states that display fine structure are those for which the 5d electron is in the lowest crystal-field level but the 4f N21 core is in a highly excited state, indicating that the broadening depends only on the energy of the 5d electron and not on the total energy of the 4f N21 5d excited state.
Journal of Physics: Condensed Matter, 2011
Journal of Physics: Condensed Matter, 2013
Calculated energy levels from recent ab initio studies of the electronic structure of SrCl 2 :Yb ... more Calculated energy levels from recent ab initio studies of the electronic structure of SrCl 2 :Yb 2+ and CsCaBr 3 :Yb 2+ are fitted with a semi-empirical "crystal-field" Hamiltonian, which acts within the model space 4f 14 +4f 13 5d+4f 13 6s. Parameters are obtained for the minima of the potential-energy curves for each energy level and also for a range of anion-cation separations. The parameters are compared with published parameters fitted to experimental data and to atomic calculations. The states with significant 4f 13 6s character give a good approximation to the impurity-trapped exciton states that appear in the ab initio calculations.
Journal of Luminescence, 2013
CaF 2 :Yb 2+ and SrF 2 :Yb 2+ crystals have been investigated by a two-color UV + IR transient ph... more CaF 2 :Yb 2+ and SrF 2 :Yb 2+ crystals have been investigated by a two-color UV + IR transient photoluminescence enhancement technique. The enhancement gives information about both changes in internal energy levels of the excitons and liberation of electrons from traps in the crystals.
The Journal of Chemical Physics, 2005
Journal of Alloys and Compounds, 2004
The 4f N ↔ 4f N−1 5d transition model proposed by Duan et al. [Phys. Rev. B 66 (2002) 155108] and... more The 4f N ↔ 4f N−1 5d transition model proposed by Duan et al. [Phys. Rev. B 66 (2002) 155108] and Duan and Reid [J. Solid State Chem. 171 (2003) 299] is presented in detail and extended to allow explicit calculation of line strengths of transitions between any two multiplet states by using Racah-Wigner algebra. This extended model is used to simulate the 4f 2 5d → 4f 3 emission spectrum of Nd 3+ in YPO 4 crystal.
Current Applied Physics, 2006
For emitters embedded in media of various refractive indices, different theoretical models predic... more For emitters embedded in media of various refractive indices, different theoretical models predicted substantially different dependencies of the spontaneous emission lifetime on refractive index. It has been claimed that various measurements on 4f → 4f radiative transition of Eu 3+ in hosts with variable refractive index appear to favor the real-cavity model [J. Fluoresc. 13, 201 (2003) and references therein, Phys. Rev. Lett. 91, 203903 (2003)]. We notice that 5d → 4f radiative transition of rare-earth ions, dominated by allowed electric-dipole transitions with line strengths less perturbed by the ligands, serves as a better test of different models. We analyze the lifetimes of 5d → 4f transition of Ce 3+ in hosts of refractive indices varying from 1.4 to 2.2. The results favor the macroscopic virtual-cavity model based on Lorentz local field [
Current Applied Physics, 2006
The f → d transition model by Duan and co-workers [Phys. Rev. B 66, 155108 (2002); J. Solid State... more The f → d transition model by Duan and co-workers [Phys. Rev. B 66, 155108 (2002); J. Solid State Chem. 171, 299 (2003)] has been very useful in interpreting the f → d absorption, emission and nonradiative relaxation of light lanthanide ions in crystals. However, based on the assumption that the f N −1 core spin-orbit interaction is weak compared to f → d exchange interaction, this model, in the original form, is not applicable to interpretation of the f → d transitions of heavy lanthanide ions or actinide ions in crystals. In this work the model is extended to cover the cases of heavy lanthanides and actinides, where the spin-orbit interaction of f orbitals may be stronger than the f − d exchange interaction.
Physical Review B, 2005
High-resolution 4f n−1 5d → 4f n emission spectra in the ͑vacuum͒ ultraviolet are reported for Ce... more High-resolution 4f n−1 5d → 4f n emission spectra in the ͑vacuum͒ ultraviolet are reported for Ce 3+ , Pr 3+ , Nd 3+ , Er 3+ , and Tm 3+ in LiYF 4 and YPO 4 host lattices. The positions and intensities of the zero-phonon lines are calculated and compared to the high-resolution emission spectra. For the thulium samples gated detection has been used to distinguish between the spin-forbidden and spin-allowed 4f n−1 5d → 4f n emissions. Luminescence lifetimes for the spin-forbidden 4f n−1 5d → 4f n emissions are calculated and compared with experimentally observed lifetimes. A good agreement between experiment and theory is found, demonstrating the validity of the model developed for the 4f n−1 5d and 4f n states of lanthanide ions.
Using high-performance computing techniques and targeted experimental investigation we have devel... more Using high-performance computing techniques and targeted experimental investigation we have developed a predictive crystal-field model of the complex hyperfine structure of 167 Er 3+ :Y2SiO5. We simultaneously match site-selective spectroscopic data up to 20,000 cm −1 , rotational Zeeman data, and ground-and excited-state hyperfine structure determined from high-resolution Ramanheterodyne spectroscopy on the 1.5 µm telecom transition. We achieve agreement of better than 50 MHz for assigned hyperfine transitions. The successful analysis of the complex hyperfine patterns opens the possibility of systematically searching this whole class of materials for the ZEFOZ transitions that have proved so useful in quantum information applications.
Physical Review B, 2021
We report on the development and application of a parametrized crystal-field model for both C1 sy... more We report on the development and application of a parametrized crystal-field model for both C1 symmetry centers in trivalent erbium-doped Y2SiO5. High resolution Zeeman and temperature dependent absorption spectroscopy was performed to acquire the necessary experimental data. The obtained data, in addition to the ground (4 I 15/2 Z1) state and exited (4 I 13/2 Y1) state Zeeman and hyperfine structure, was simultaneously fitted in order to refine an existing crystal-field interpretation of the Er 3+ :Y2SiO5 system. We demonstrate that it is possible to account for the electronic, magnetic and hyperfine structure of the full 4f 11 configuration of Er 3+ :Y2SiO5 and further, that it is possible to predict both optical polarization behavior and high magnetic field hyperfine structure of transitions in the 1.5 µm telecommunications band.
Physical Review B, 2021
High-resolution Zeeman spectroscopy of electronic-nuclear hyperfine levels of 5 I8 → 5 I7 transit... more High-resolution Zeeman spectroscopy of electronic-nuclear hyperfine levels of 5 I8 → 5 I7 transitions in Ho 3+ :Y2SiO5 is reported. Crystal-field parameters determined for the two C1 symmetry sites in Er 3+ :Y2SiO5 are successfully used to model the Zeeman-hyperfine data, including the prediction of avoided crossings between hyperfine levels under the influence of an external magnetic field. The two six-and seven-coordinate substitutional sites may be distinguished by comparing the spectra with crystal-field calculations.
Журнал технической физики, 2019
Zeeman spectroscopy is used to demonstrate that phenomenological crystal-field parameters determi... more Zeeman spectroscopy is used to demonstrate that phenomenological crystal-field parameters determined for the two C _1 point-group symmetry sites in Er^3+:Y_2SiO_5 may be transferred to other ions. The two crystallographic six-and seven-coordinate substitutional sites may be distinguished by comparing the spectra with crystal-field calculations.
Journal of Physics: Condensed Matter, 2018
We present a comprehensive spectroscopic study of C 2v point-group symmetry sites in Sm 3+ :CaF 2... more We present a comprehensive spectroscopic study of C 2v point-group symmetry sites in Sm 3+ :CaF 2 /SrF 2 codoped with either NaF or LiF. Data includes electron paramagnetic resonance measurements of Zeeman and hyperfine interactions for the ground state, as well as site-selective excitation and fluorescence spectroscopy up to the 4 G 5/2 multiplet. Inclusion of the EPR data allowed us to determine unique crystalfield parameters. The parameters provide information about the geometry of the sites and the nature of the interactions between the Sm 3+ dopant and the alkaline earth co-dopant.
Physics Letters A, 2005
For emitters embedded in media of various refractive indices, different macroscopic or microscopi... more For emitters embedded in media of various refractive indices, different macroscopic or microscopic theoretical models predict different dependencies of the spontaneous emission lifetime on refractive index. Among those models are the two most promising models: the virtual-cavity model and the real-cavity model. It is a priori not clear which model is more relevant for a given situation. By close analysis of the available experimental results and examining the assumptions underlying the two models, we reach a consistent interpretation of the experimental results and give the criteria which model should apply for a given situation.
The 4 f n →4 f nϪ1 5d(f d) excitation spectra of the heavy lanthanides (Tb 3ϩ , Dy 3ϩ , Ho 3ϩ , E... more The 4 f n →4 f nϪ1 5d(f d) excitation spectra of the heavy lanthanides (Tb 3ϩ , Dy 3ϩ , Ho 3ϩ , Er 3ϩ , Tm 3ϩ , and Yb 3ϩ) incorporated in LiYF 4 , CaF 2 , and YPO 4 are investigated in the ultraviolet and vacuum-ultraviolet spectral region ͑100-275 nm͒. Spin-forbidden transitions as well as spin-allowed transitions are observed for all heavy lanthanides. In the excitation spectra the crystal-field splitting of the 5d electron can be clearly observed. Fine structure ͑zero-phonon lines and vibronic lines͒ is observed for the transition to the lowest 5d crystal-field component, for both the high-spin and low-spin fd bands. Energy-level and intensity calculations are performed by an extension of the commonly used model for energy-level calculations of 4 f n states. A good agreement between experimental and simulated spectra is obtained, using parameters that describe the 5d crystal-field splitting ͑from the spectra of Ce 3ϩ), the parameters for the splitting of the 4 f nϪ1 core ͑from the literature on energy-level calculations for 4 f n states͒ and parameters for the spin-orbit coupling of the 5d electron and the Coulomb interaction between 4 f and 5d electrons ͑from atomic ab initio calculations using the computer code of Cowan͒. To improve the agreement between the model and experiment, the 5d crystalfield parameters were adjusted slightly to correct for the decreasing crystal-field strength for the heavier rare earths due to the lanthanide contraction. The f-d interaction parameters in the fluoride host lattices were reduced to about 67% of the calculated free-ion values in order to compensate for the nephelauxetic effect.
Physical Review Letters, 1993
Burdick and Reid Reply: In our Letter [1] we emphasized the advantages of a many-body perturbatio... more Burdick and Reid Reply: In our Letter [1] we emphasized the advantages of a many-body perturbation theory (MBPT) formalism [2] for transition intensity calcula-(8)
The Journal of Physical Chemistry B, 2006
Detailed analysis of the vibronic structure in the electronic absorption spectrum of Cs 2 NaYbF 6... more Detailed analysis of the vibronic structure in the electronic absorption spectrum of Cs 2 NaYbF 6 at temperatures between 10 and 300 K enables the crystal field energy level diagram of Yb 3+ in this cubic host to be deduced. Ultraviolet and visible laser excitation of Cs 2 NaYbF 6 , Cs 2 NaY 0.9 Yb 0.1 F 6 , and Cs 2 NaHo 0.99 Yb 0.01 F 6 give spectral features mainly due to Yb 3+ being situated at a range of defect sites. The 4f 13 crystal field analyses of octahedral YbX 6 3-(X) F, Cl, Br) systems show the expected trends in parameter values, but the energy level fits are poor. Inclusion of the interaction with the charge-transfer configuration 4f 14 np 5 provides an exact fitting of energy levels for YbX 6 3-, and a smooth variation of ff and fp crystal field parameters for Cs 2 NaLnCl 6 (Ln) Er, Tm, Yb) is observed.
Physical Review Letters, 2002
High-energy transitions in the 4f N ! 4f N21 5d excitation spectra of lanthanide ions in host cry... more High-energy transitions in the 4f N ! 4f N21 5d excitation spectra of lanthanide ions in host crystals are usually broadened due to the short excited-state lifetimes, whereas low-energy transitions, with longer excited-state lifetimes, may show fine structure. We report the surprising observation that for some materials fine structure is observed not only for the low-energy excitation bands but also for some highenergy transitions. The excited states that display fine structure are those for which the 5d electron is in the lowest crystal-field level but the 4f N21 core is in a highly excited state, indicating that the broadening depends only on the energy of the 5d electron and not on the total energy of the 4f N21 5d excited state.
Journal of Physics: Condensed Matter, 2011
Journal of Physics: Condensed Matter, 2013
Calculated energy levels from recent ab initio studies of the electronic structure of SrCl 2 :Yb ... more Calculated energy levels from recent ab initio studies of the electronic structure of SrCl 2 :Yb 2+ and CsCaBr 3 :Yb 2+ are fitted with a semi-empirical "crystal-field" Hamiltonian, which acts within the model space 4f 14 +4f 13 5d+4f 13 6s. Parameters are obtained for the minima of the potential-energy curves for each energy level and also for a range of anion-cation separations. The parameters are compared with published parameters fitted to experimental data and to atomic calculations. The states with significant 4f 13 6s character give a good approximation to the impurity-trapped exciton states that appear in the ab initio calculations.
Journal of Luminescence, 2013
CaF 2 :Yb 2+ and SrF 2 :Yb 2+ crystals have been investigated by a two-color UV + IR transient ph... more CaF 2 :Yb 2+ and SrF 2 :Yb 2+ crystals have been investigated by a two-color UV + IR transient photoluminescence enhancement technique. The enhancement gives information about both changes in internal energy levels of the excitons and liberation of electrons from traps in the crystals.
The Journal of Chemical Physics, 2005
Journal of Alloys and Compounds, 2004
The 4f N ↔ 4f N−1 5d transition model proposed by Duan et al. [Phys. Rev. B 66 (2002) 155108] and... more The 4f N ↔ 4f N−1 5d transition model proposed by Duan et al. [Phys. Rev. B 66 (2002) 155108] and Duan and Reid [J. Solid State Chem. 171 (2003) 299] is presented in detail and extended to allow explicit calculation of line strengths of transitions between any two multiplet states by using Racah-Wigner algebra. This extended model is used to simulate the 4f 2 5d → 4f 3 emission spectrum of Nd 3+ in YPO 4 crystal.
Current Applied Physics, 2006
For emitters embedded in media of various refractive indices, different theoretical models predic... more For emitters embedded in media of various refractive indices, different theoretical models predicted substantially different dependencies of the spontaneous emission lifetime on refractive index. It has been claimed that various measurements on 4f → 4f radiative transition of Eu 3+ in hosts with variable refractive index appear to favor the real-cavity model [J. Fluoresc. 13, 201 (2003) and references therein, Phys. Rev. Lett. 91, 203903 (2003)]. We notice that 5d → 4f radiative transition of rare-earth ions, dominated by allowed electric-dipole transitions with line strengths less perturbed by the ligands, serves as a better test of different models. We analyze the lifetimes of 5d → 4f transition of Ce 3+ in hosts of refractive indices varying from 1.4 to 2.2. The results favor the macroscopic virtual-cavity model based on Lorentz local field [
Current Applied Physics, 2006
The f → d transition model by Duan and co-workers [Phys. Rev. B 66, 155108 (2002); J. Solid State... more The f → d transition model by Duan and co-workers [Phys. Rev. B 66, 155108 (2002); J. Solid State Chem. 171, 299 (2003)] has been very useful in interpreting the f → d absorption, emission and nonradiative relaxation of light lanthanide ions in crystals. However, based on the assumption that the f N −1 core spin-orbit interaction is weak compared to f → d exchange interaction, this model, in the original form, is not applicable to interpretation of the f → d transitions of heavy lanthanide ions or actinide ions in crystals. In this work the model is extended to cover the cases of heavy lanthanides and actinides, where the spin-orbit interaction of f orbitals may be stronger than the f − d exchange interaction.
Physical Review B, 2005
High-resolution 4f n−1 5d → 4f n emission spectra in the ͑vacuum͒ ultraviolet are reported for Ce... more High-resolution 4f n−1 5d → 4f n emission spectra in the ͑vacuum͒ ultraviolet are reported for Ce 3+ , Pr 3+ , Nd 3+ , Er 3+ , and Tm 3+ in LiYF 4 and YPO 4 host lattices. The positions and intensities of the zero-phonon lines are calculated and compared to the high-resolution emission spectra. For the thulium samples gated detection has been used to distinguish between the spin-forbidden and spin-allowed 4f n−1 5d → 4f n emissions. Luminescence lifetimes for the spin-forbidden 4f n−1 5d → 4f n emissions are calculated and compared with experimentally observed lifetimes. A good agreement between experiment and theory is found, demonstrating the validity of the model developed for the 4f n−1 5d and 4f n states of lanthanide ions.