The fluorescence line narrowing (FLN) of the N 1 and N 2 lines of pairs of Cr 3+ ions in concentrated ruby has been studied. The structure of the narrowed lines has been explained and measurements of the homogeneous width have been improved. By use of the FLN and time-resolved spectroscopy, spectral transfer within the N 1 line has been investigated. A two-phonon-assisted process has been found to be responsible for the transfer.

Journal of Physics C Solid State PhysicsOct 20, 19843 citations

IEEE Journal of Quantum Electronics

7B5 - Energy transfer in ruby

G. F. Imbusch

Published Sep 1, 1966• 4 citations

Publisher

Abstract

DOI: 10.1109/jqe.1966.1074129

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Energy transfer in ruby

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The transfer of energy from single chromium ions to closely coupled pairs of chromium ions in ruby has been investigated. Ruby samples whose concentrations ranged from 0.003 to 1.0% ${\mathrm{Cr}}_{2}$ ${\mathrm{O}}_{3}$ were prepared and in each crystal the intensity of single-ion fluorescence and of pair fluorescence was accurately measured. Radiative-decay measurements were also made in an attempt to unravel the dynamics of the transfer process. The transfer from single ions to pairs is shown to occur nonradiatively, and its efficiency is enhanced by a fast energy transfer between individual single ions. The possibility is explored that an electric quadrupole-quadrupole interaction is responsible for this transfer process.The transfer of energy from single chromium ions to closely coupled pairs of chromium ions in ruby has been investigated. Ruby samples whose concentrations ranged from 0.003 to 1.0% ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$ were prepared and in each crystal the intensity of single-ion fluorescence and of pair fluorescence was accurately measured. Radiative-decay measurements were also made in an attempt to unravel the dynamics of the transfer process. The transfer from single ions to pairs is shown to occur nonradiatively, and its efficiency is enhanced by a fast energy transfer between individual single ions. The possibility is explored that an electric quadrupole-quadrupole interaction is responsible for this transfer process.

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Critical Concentration for Single-Ion-Single-Ion Energy Transfer in Ruby

S. K. Lyo

The critical concentration for single-ion-single-ion energy transfer in ruby is calculated using Anderson's method for transport between ions which are characterized by inhomogeneously broadened energy levels. The excitation on the chromium impurity is assumed to propagate by virtue of superexchange interactions. Using a continuum approximation, we find that the single-ion excitation is localized below concentrations of \ensuremath{\sim}0.3-0.4%, a range not inconsistent with that concentration at which a sudden change in the fluorescent lifetime of ruby occurs.The critical concentration for single-ion-single-ion energy transfer in ruby is calculated using Anderson's method for transport between ions which are characterized by inhomogeneously broadened energy levels. The excitation on the chromium impurity is assumed to propagate by virtue of superexchange interactions. Using a continuum approximation, we find that the single-ion excitation is localized below concentrations of \ensuremath{\sim}0.3-0.4%, a range not inconsistent with that concentration at which a sudden change in the fluorescent lifetime of ruby occurs.

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Fluorescence Studies of Energy Transfer between Single and Pair Cr3+ Systems in Al2 O3

Richard C. Powell, Baldassare Di Bartolo, Behzad Birang +1 more

The fluorescence intensities and lifetimes of various no-phonon lines in ruby samples with 2.1 and 0.94% ${\mathrm{Cr}}^{3+}$ were studied from 13 to 700\ifmmode^\circ\else\textdegree\fi{}K. The temperature dependences of the intensities of numerous lines were used to determine the energy levels of two pair systems. The relative intensities of the single-ion ( $R$ ) lines and the pair ( $N$ ) lines are proportional to Boltzmann factors ${e}^{\frac{\ensuremath{-}\ensuremath{\Delta}E}{\mathrm{kT}}}$, where $\ensuremath{\Delta}E$ is the difference in energy of the metastable states, at high temperatures but not at low temperatures. The deviation from this law is greater and occurs at higher temperatures in the less concentrated sample. The fluorescence decays of the $R$ and $N$ lines are pure exponentials in the temperature region where the $N$ lines follow a Boltzmann law; at low temperatures the $N$ lines have an initial rise in fluorescence and then a decay. These results are interpreted in terms of coupled fluorescence systems consisting of single ions and pairs. A phonon-assisted cross-relaxation coupling process is suggested which allows for thermalization of the systems at high temperatures and direct pumping of the pair systems by the single-ion system at low temperatures. Energy transfer from single-ion to multi-ion systems was also observed.The fluorescence intensities and lifetimes of various no-phonon lines in ruby samples with 2.1 and 0.94% ${\mathrm{Cr}}^{3+}$ were studied from 13 to 700\ifmmode^\circ\else\textdegree\fi{}K. The temperature dependences of the intensities of numerous lines were used to determine the energy levels of two pair systems. The relative intensities of the single-ion ($R$) lines and the pair ($N$) lines are proportional to Boltzmann factors ${e}^{\frac{\ensuremath{-}\ensuremath{\Delta}E}{\mathrm{kT}}}$, where $\ensuremath{\Delta}E$ is the difference in energy of the metastable states, at high temperatures but not at low temperatures. The deviation from this law is greater and occurs at higher temperatures in the less concentrated sample. The fluorescence decays of the $R$ and $N$ lines are pure exponentials in the temperature region where the $N$ lines follow a Boltzmann law; at low temperatures the $N$ lines have an initial rise in fluorescence and then a decay. These results are interpreted in terms of coupled fluorescence systems consisting of single ions and pairs. A phonon-assisted cross-relaxation coupling process is suggested which allows for thermalization of the systems at high temperatures and direct pumping of the pair systems by the single-ion system at low temperatures. Energy transfer from single-ion to multi-ion systems was also observed.

Physical ReviewMar 10, 196764 citations

Fluorescence-line-narrowing and energy-transfer studies in ruby

Peter M. Selzer, David L. Huber, B. B. Barnett +1 more

Fluorescence-line-narrowing and time-resolved studies have been conducted in ruby crystals and powders, in concentrations varying from 0.025 to 0.9 at.%. The resonance fluorescence component of the ${R}_{1}$ line at low temperatures is observed to increase dramatically as the laser is tuned from line center toward the low-energy wing of the inhomogeneously broadened absorption. This is presumed to indicate the presence of weakly coupled pairs in the wings of the line. Intraline and interline (${R}_{1}\ensuremath{\rightarrow}{N}_{1,2}$) energy transfer have also been studied, and an elaboration of earlier work is given. Time-resolved selective-excitation scans have revealed numerous channels in the vicinity of the $R$ lines by which the different pairs can be directly excited. These are assumed to be Cr ions near enough to a pair to be in a highly perturbed environment. Various experimental results are shown to be consistent with a model of rapid transfer between resonant Cr ions which feeds the pairs via a weak, nonresonant coupling to these perturbed ions. Macroscopic strain broadening is also shown to be favored over microscopic broadening, and the implications for Anderson localization in ruby are discussed.Fluorescence-line-narrowing and time-resolved studies have been conducted in ruby crystals and powders, in concentrations varying from 0.025 to 0.9 at.%. The resonance fluorescence component of the ${R}_{1}$ line at low temperatures is observed to increase dramatically as the laser is tuned from line center toward the low-energy wing of the inhomogeneously broadened absorption. This is presumed to indicate the presence of weakly coupled pairs in the wings of the line. Intraline and interline (${R}_{1}\ensuremath{\rightarrow}{N}_{1,2}$) energy transfer have also been studied, and an elaboration of earlier work is given. Time-resolved selective-excitation scans have revealed numerous channels in the vicinity of the $R$ lines by which the different pairs can be directly excited. These are assumed to be Cr ions near enough to a pair to be in a highly perturbed environment. Various experimental results are shown to be consistent with a model of rapid transfer between resonant Cr ions which feeds the pairs via a weak, nonresonant coupling to these perturbed ions. Macroscopic strain broadening is also shown to be favored over microscopic broadening, and the implications for Anderson localization in ruby are discussed.

Physical review. B, Condensed matterJun 15, 197891 citations

Fluorescence line narrowing and spectral energy transfer in pair lines of ruby

André Monteil, Eugène Duval

Journal of Physics C Solid State PhysicsOct 20, 19843 citations

The transfer of energy from single chromium ions to closely coupled pairs of chromium ions in ruby has been investigated. Ruby samples whose concentrations ranged from 0.003 to 1.0%

{\mathrm{Cr}}_{2}

{\mathrm{O}}_{3}

were prepared and in each crystal the intensity of single-ion fluorescence and of pair fluorescence was accurately measured. Radiative-decay measurements were also made in an attempt to unravel the dynamics of the transfer process. The transfer from single ions to pairs is shown to occur nonradiatively, and its efficiency is enhanced by a fast energy transfer between individual single ions. The possibility is explored that an electric quadrupole-quadrupole interaction is responsible for this transfer process.

The transfer of energy from single chromium ions to closely coupled pairs of chromium ions in ruby has been investigated. Ruby samples whose concentrations ranged from 0.003 to 1.0%

{\mathrm{Cr}}_{2}

{\mathrm{O}}_{3}

The fluorescence intensities and lifetimes of various no-phonon lines in ruby samples with 2.1 and 0.94%

{\mathrm{Cr}}^{3+}

were studied from 13 to 700\ifmmode^\circ\else\textdegree\fi{}K. The temperature dependences of the intensities of numerous lines were used to determine the energy levels of two pair systems. The relative intensities of the single-ion (

R

) lines and the pair (

N

) lines are proportional to Boltzmann factors ${e}^{\frac{\ensuremath{-}\ensuremath{\Delta}E}{\mathrm{kT}}}$, where $\ensuremath{\Delta}E$ is the difference in energy of the metastable states, at high temperatures but not at low temperatures. The deviation from this law is greater and occurs at higher temperatures in the less concentrated sample. The fluorescence decays of the

R

and

N

lines are pure exponentials in the temperature region where the

N

lines follow a Boltzmann law; at low temperatures the

N

lines have an initial rise in fluorescence and then a decay. These results are interpreted in terms of coupled fluorescence systems consisting of single ions and pairs. A phonon-assisted cross-relaxation coupling process is suggested which allows for thermalization of the systems at high temperatures and direct pumping of the pair systems by the single-ion system at low temperatures. Energy transfer from single-ion to multi-ion systems was also observed.

Fluorescence-line-narrowing and time-resolved studies have been conducted in ruby crystals and powders, in concentrations varying from 0.025 to 0.9 at.%. The resonance fluorescence component of the

{R}_{1}

line at low temperatures is observed to increase dramatically as the laser is tuned from line center toward the low-energy wing of the inhomogeneously broadened absorption. This is presumed to indicate the presence of weakly coupled pairs in the wings of the line. Intraline and interline (${R}_{1}\ensuremath{\rightarrow}{N}_{1,2}$) energy transfer have also been studied, and an elaboration of earlier work is given. Time-resolved selective-excitation scans have revealed numerous channels in the vicinity of the

R

lines by which the different pairs can be directly excited. These are assumed to be Cr ions near enough to a pair to be in a highly perturbed environment. Various experimental results are shown to be consistent with a model of rapid transfer between resonant Cr ions which feeds the pairs via a weak, nonresonant coupling to these perturbed ions. Macroscopic strain broadening is also shown to be favored over microscopic broadening, and the implications for Anderson localization in ruby are discussed.