The Experts below are selected from a list of 32532 Experts worldwide ranked by ideXlab platform
Wenwu Cao - One of the best experts on this subject based on the ideXlab platform.
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origin of the deviation between the fluorescence intensity ratio of a thermally coupled level and the Boltzmann Distribution law
EPL, 2016Co-Authors: Feng Qin, Zhiguo Zhang, Wenwu Cao, Hua Zhao, Wei CaiAbstract:The temperature dependence of the fluorescence intensities of the thermally coupled pairs of some typical rare-earth ions was studied. The fluorescence intensity ratios (FIRs) of the thermally coupled pairs increased exponentially with increasing temperature. However, except for Er3+ and Nd3+, the FIRs of other rare-earth ions exhibited significant deviation from the Boltzmann Distribution law. We suppose the deviation originates from the non-thermal population in the upper level of the coupled pairs. The temperature dependence of the deviation is discussed. Eliminating the deviation is beneficial for the development of FIR thermometry; only by clearly understanding the deviation can we eliminate it.
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a precise Boltzmann Distribution law for the fluorescence intensity ratio of two thermally coupled levels
Applied Physics Letters, 2016Co-Authors: Feng Qin, Zhiguo Zhang, Wenwu Cao, Hua Zhao, Wei CaiAbstract:Noncontact monitoring temperature is very important in modern medicine, science, and technologies. The fluorescence intensity ratio (FIR) technique based on the Boltzmann Distribution law exhibits excellent application potential, but the observed FIR deviates from the Boltzmann Distribution law in the low temperature range. We propose a fluorescence intensity ratio relation FIR* = ηFIR by introducing a quantity η representing thermal population degree, which can be obtained from measured fluorescence decay curves of the upper emitting level. Using Eu3+ as an example, the method is confirmed that the deviated FIR is able to be corrected and return to follow the Boltzmann law.
Feng Qin - One of the best experts on this subject based on the ideXlab platform.
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origin of the deviation between the fluorescence intensity ratio of a thermally coupled level and the Boltzmann Distribution law
EPL, 2016Co-Authors: Feng Qin, Zhiguo Zhang, Wenwu Cao, Hua Zhao, Wei CaiAbstract:The temperature dependence of the fluorescence intensities of the thermally coupled pairs of some typical rare-earth ions was studied. The fluorescence intensity ratios (FIRs) of the thermally coupled pairs increased exponentially with increasing temperature. However, except for Er3+ and Nd3+, the FIRs of other rare-earth ions exhibited significant deviation from the Boltzmann Distribution law. We suppose the deviation originates from the non-thermal population in the upper level of the coupled pairs. The temperature dependence of the deviation is discussed. Eliminating the deviation is beneficial for the development of FIR thermometry; only by clearly understanding the deviation can we eliminate it.
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a precise Boltzmann Distribution law for the fluorescence intensity ratio of two thermally coupled levels
Applied Physics Letters, 2016Co-Authors: Feng Qin, Zhiguo Zhang, Wenwu Cao, Hua Zhao, Wei CaiAbstract:Noncontact monitoring temperature is very important in modern medicine, science, and technologies. The fluorescence intensity ratio (FIR) technique based on the Boltzmann Distribution law exhibits excellent application potential, but the observed FIR deviates from the Boltzmann Distribution law in the low temperature range. We propose a fluorescence intensity ratio relation FIR* = ηFIR by introducing a quantity η representing thermal population degree, which can be obtained from measured fluorescence decay curves of the upper emitting level. Using Eu3+ as an example, the method is confirmed that the deviated FIR is able to be corrected and return to follow the Boltzmann law.
Stuart C Althorpe - One of the best experts on this subject based on the ideXlab platform.
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Boltzmann conserving classical dynamics in quantum time correlation functions matsubara dynamics
arXiv: Chemical Physics, 2015Co-Authors: Timothy J H Hele, Michael J Willatt, Andrea Muolo, Stuart C AlthorpeAbstract:We show that a single change in the derivation of the linearized semiclassical-initial value representation (LSC-IVR or classical Wigner approximation) results in a classical dynamics which conserves the quantum Boltzmann Distribution. We rederive the (standard) LSC-IVR approach by writing the (exact) quantum time-correlation function in terms of the normal modes of a free ring-polymer (i.e. a discrete imaginary-time Feynman path), taking the limit that the number of polymer beads $N \to \infty$, such that the lowest normal-mode frequencies take their Matsubara values. The change we propose is to truncate the quantum Liouvillian, not explicitly in powers of $\hbar^2$ at $\hbar^0$ (which gives back the standard LSC-IVR approximation), but in the normal-mode derivatives corresponding to the lowest Matsubara frequencies. The resulting Matsubara dynamics is inherently classical (since all terms $\mathcal{O}\left(\hbar^{2}\right)$ disappear from the Matsubara Liouvillian in the limit $N \to \infty$), and conserves the quantum Boltzmann Distribution because the Matsubara Hamiltonian is symmetric with respect to imaginary-time translation. Numerical tests show that the Matsubara approximation to the quantum time-correlation function converges with respect to the number of modes, and gives better agreement than LSC- IVR with the exact quantum result. Matsubara dynamics is too computationally expensive to be applied to complex systems, but its further approximation may lead to practical methods.
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Boltzmann conserving classical dynamics in quantum time correlation functions matsubara dynamics
Journal of Chemical Physics, 2015Co-Authors: Timothy J H Hele, Michael J Willatt, Andrea Muolo, Stuart C AlthorpeAbstract:We show that a single change in the derivation of the linearized semiclassical-initial value representation (LSC-IVR or “classical Wigner approximation”) results in a classical dynamics which conserves the quantum Boltzmann Distribution. We rederive the (standard) LSC-IVR approach by writing the (exact) quantum time-correlation function in terms of the normal modes of a free ring-polymer (i.e., a discrete imaginary-time Feynman path), taking the limit that the number of polymer beads N → ∞, such that the lowest normal-mode frequencies take their “Matsubara” values. The change we propose is to truncate the quantum Liouvillian, not explicitly in powers of ħ2 at ħ0 (which gives back the standard LSC-IVR approximation), but in the normal-mode derivatives corresponding to the lowest Matsubara frequencies. The resulting “Matsubara” dynamics is inherently classical (since all terms O(ħ2) disappear from the Matsubara Liouvillian in the limit N → ∞) and conserves the quantum Boltzmann Distribution because the Mats...
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Boltzmann conserving classical dynamics in quantum time correlation functions matsubara dynamics
Journal of Chemical Physics, 2015Co-Authors: Timothy J H Hele, Michael J Willatt, Andrea Muolo, Stuart C AlthorpeAbstract:We show that a single change in the derivation of the linearized semiclassical-initial value representation (LSC-IVR or "classical Wigner approximation") results in a classical dynamics which conserves the quantum Boltzmann Distribution. We rederive the (standard) LSC-IVR approach by writing the (exact) quantum time-correlation function in terms of the normal modes of a free ring-polymer (i.e., a discrete imaginary-time Feynman path), taking the limit that the number of polymer beads N → ∞, such that the lowest normal-mode frequencies take their "Matsubara" values. The change we propose is to truncate the quantum Liouvillian, not explicitly in powers of ħ(2) at ħ(0) (which gives back the standard LSC-IVR approximation), but in the normal-mode derivatives corresponding to the lowest Matsubara frequencies. The resulting "Matsubara" dynamics is inherently classical (since all terms O(ħ(2)) disappear from the Matsubara Liouvillian in the limit N → ∞) and conserves the quantum Boltzmann Distribution because the Matsubara Hamiltonian is symmetric with respect to imaginary-time translation. Numerical tests show that the Matsubara approximation to the quantum time-correlation function converges with respect to the number of modes and gives better agreement than LSC-IVR with the exact quantum result. Matsubara dynamics is too computationally expensive to be applied to complex systems, but its further approximation may lead to practical methods.
Wei Cai - One of the best experts on this subject based on the ideXlab platform.
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origin of the deviation between the fluorescence intensity ratio of a thermally coupled level and the Boltzmann Distribution law
EPL, 2016Co-Authors: Feng Qin, Zhiguo Zhang, Wenwu Cao, Hua Zhao, Wei CaiAbstract:The temperature dependence of the fluorescence intensities of the thermally coupled pairs of some typical rare-earth ions was studied. The fluorescence intensity ratios (FIRs) of the thermally coupled pairs increased exponentially with increasing temperature. However, except for Er3+ and Nd3+, the FIRs of other rare-earth ions exhibited significant deviation from the Boltzmann Distribution law. We suppose the deviation originates from the non-thermal population in the upper level of the coupled pairs. The temperature dependence of the deviation is discussed. Eliminating the deviation is beneficial for the development of FIR thermometry; only by clearly understanding the deviation can we eliminate it.
-
a precise Boltzmann Distribution law for the fluorescence intensity ratio of two thermally coupled levels
Applied Physics Letters, 2016Co-Authors: Feng Qin, Zhiguo Zhang, Wenwu Cao, Hua Zhao, Wei CaiAbstract:Noncontact monitoring temperature is very important in modern medicine, science, and technologies. The fluorescence intensity ratio (FIR) technique based on the Boltzmann Distribution law exhibits excellent application potential, but the observed FIR deviates from the Boltzmann Distribution law in the low temperature range. We propose a fluorescence intensity ratio relation FIR* = ηFIR by introducing a quantity η representing thermal population degree, which can be obtained from measured fluorescence decay curves of the upper emitting level. Using Eu3+ as an example, the method is confirmed that the deviated FIR is able to be corrected and return to follow the Boltzmann law.
Zhiguo Zhang - One of the best experts on this subject based on the ideXlab platform.
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origin of the deviation between the fluorescence intensity ratio of a thermally coupled level and the Boltzmann Distribution law
EPL, 2016Co-Authors: Feng Qin, Zhiguo Zhang, Wenwu Cao, Hua Zhao, Wei CaiAbstract:The temperature dependence of the fluorescence intensities of the thermally coupled pairs of some typical rare-earth ions was studied. The fluorescence intensity ratios (FIRs) of the thermally coupled pairs increased exponentially with increasing temperature. However, except for Er3+ and Nd3+, the FIRs of other rare-earth ions exhibited significant deviation from the Boltzmann Distribution law. We suppose the deviation originates from the non-thermal population in the upper level of the coupled pairs. The temperature dependence of the deviation is discussed. Eliminating the deviation is beneficial for the development of FIR thermometry; only by clearly understanding the deviation can we eliminate it.
-
a precise Boltzmann Distribution law for the fluorescence intensity ratio of two thermally coupled levels
Applied Physics Letters, 2016Co-Authors: Feng Qin, Zhiguo Zhang, Wenwu Cao, Hua Zhao, Wei CaiAbstract:Noncontact monitoring temperature is very important in modern medicine, science, and technologies. The fluorescence intensity ratio (FIR) technique based on the Boltzmann Distribution law exhibits excellent application potential, but the observed FIR deviates from the Boltzmann Distribution law in the low temperature range. We propose a fluorescence intensity ratio relation FIR* = ηFIR by introducing a quantity η representing thermal population degree, which can be obtained from measured fluorescence decay curves of the upper emitting level. Using Eu3+ as an example, the method is confirmed that the deviated FIR is able to be corrected and return to follow the Boltzmann law.