Limits...
Defect induced changes on the excitation transfer dynamics in ZnS/Mn nanowires.

Kaiser U, Chen L, Geburt S, Ronning C, Heimbrodt W - Nanoscale Res Lett (2011)

Bottom Line: The transients of the Mn-related luminescence can be quantitatively described on the basis of a modified Förster model accounting for reduced dimensionality.Here, we confirm this modified Förster model by varying the number of killer centers systematically.The temporal behavior of the internal Mn2+ (3d5) luminescence is recorded on a time scale covering almost four orders of magnitude.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Material Sciences Center, Philipps-University of Marburg, Renthof 5, 35032 Marburg, Germany. limei.klar@physik.uni-marburg.de.

ABSTRACT
Transients of Mn internal 3d5 luminescence in ZnS/Mn nanowires are strongly non-exponential. This non-exponential decay arises from an excitation transfer from the Mn ions to so-called killer centers, i.e., non-radiative defects in the nanostructures and is strongly related to the interplay of the characteristic length scales of the sample such as the spatial extensions, the distance between killer centers, and the distance between Mn ions. The transients of the Mn-related luminescence can be quantitatively described on the basis of a modified Förster model accounting for reduced dimensionality. Here, we confirm this modified Förster model by varying the number of killer centers systematically. Additional defects were introduced into the ZnS/Mn nanowire samples by irradiation with neon ions and by varying the Mn implantation or the annealing temperature. The temporal behavior of the internal Mn2+ (3d5) luminescence is recorded on a time scale covering almost four orders of magnitude. A correlation between defect concentration and decay behavior of the internal Mn2+ (3d5) luminescence is established and the energy transfer processes in the system of localized Mn ions and the killer centers within ZnS/Mn nanostructures is confirmed. If the excitation transfer between Mn ions and killer centers as well as migration effects between Mn ions are accounted for, and the correct effective dimensionality of the system is used in the model, one is able to describe the decay curves of ZnS/Mn nanostructures in the entire time window.

No MeSH data available.


Related in: MedlinePlus

The experimental data and the corresponding fitted curve from Mn PL transients. ZnS/Mn wire samples with a Mn concentration of 2.8·10-3 at.%.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211286&req=5

Figure 3: The experimental data and the corresponding fitted curve from Mn PL transients. ZnS/Mn wire samples with a Mn concentration of 2.8·10-3 at.%.

Mentions: The Mn internal transition of ZnS/Mn typically shows up as a single band in the yellow range of the visible spectrum. The intensity of the Mn yellow PL spectra measured at different times after the pulsed excitation were recorded, and their intensities are plotted in the decay curve against the time after arrival of the laser pulse on the sample. We are able to follow the decay of the Mn luminescence over more than four orders of magnitude in intensity in a decay time window ranging from 1 μs to 10 ms. Figure 2 shows a series of normalized PL spectra of the yellow Mn internal transition taken at different times after the laser excitation pulse. The time values given in the figure correspond to the center of an integration time window during the decay process, which was gradually extended with the decaying time. The integration time window was set to 1 μs for the early decay times below 20 μs. It has been extended to 10 μs for all measurements between 20 and 200 μs decay times to 100 μs for all measurements between 200 μs and 2 ms decay times and finally extended to 1,000 μs for all curves taken at later decay times. The broad luminescence band centered at 580 nm is characteristic for the internal luminescence of Mn2+ incorporated on Zn sites. The symbols in Figure 3 show the decay of the Mn PL intensity of a ZnS/Mn wire sample which was implanted at 600°C. The Mn concentration of this sample is 2.8·10-3 at.%, which corresponds to a large mean distance between Mn ions of about 11.4 nm, consequently, with a low resonant energy transfer effect between the Mn atoms. The transient is characterized by a rapid decrease shortly after the laser pulse followed by a slow, but rather, exponential tail at later times.


Defect induced changes on the excitation transfer dynamics in ZnS/Mn nanowires.

Kaiser U, Chen L, Geburt S, Ronning C, Heimbrodt W - Nanoscale Res Lett (2011)

The experimental data and the corresponding fitted curve from Mn PL transients. ZnS/Mn wire samples with a Mn concentration of 2.8·10-3 at.%.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211286&req=5

Figure 3: The experimental data and the corresponding fitted curve from Mn PL transients. ZnS/Mn wire samples with a Mn concentration of 2.8·10-3 at.%.
Mentions: The Mn internal transition of ZnS/Mn typically shows up as a single band in the yellow range of the visible spectrum. The intensity of the Mn yellow PL spectra measured at different times after the pulsed excitation were recorded, and their intensities are plotted in the decay curve against the time after arrival of the laser pulse on the sample. We are able to follow the decay of the Mn luminescence over more than four orders of magnitude in intensity in a decay time window ranging from 1 μs to 10 ms. Figure 2 shows a series of normalized PL spectra of the yellow Mn internal transition taken at different times after the laser excitation pulse. The time values given in the figure correspond to the center of an integration time window during the decay process, which was gradually extended with the decaying time. The integration time window was set to 1 μs for the early decay times below 20 μs. It has been extended to 10 μs for all measurements between 20 and 200 μs decay times to 100 μs for all measurements between 200 μs and 2 ms decay times and finally extended to 1,000 μs for all curves taken at later decay times. The broad luminescence band centered at 580 nm is characteristic for the internal luminescence of Mn2+ incorporated on Zn sites. The symbols in Figure 3 show the decay of the Mn PL intensity of a ZnS/Mn wire sample which was implanted at 600°C. The Mn concentration of this sample is 2.8·10-3 at.%, which corresponds to a large mean distance between Mn ions of about 11.4 nm, consequently, with a low resonant energy transfer effect between the Mn atoms. The transient is characterized by a rapid decrease shortly after the laser pulse followed by a slow, but rather, exponential tail at later times.

Bottom Line: The transients of the Mn-related luminescence can be quantitatively described on the basis of a modified Förster model accounting for reduced dimensionality.Here, we confirm this modified Förster model by varying the number of killer centers systematically.The temporal behavior of the internal Mn2+ (3d5) luminescence is recorded on a time scale covering almost four orders of magnitude.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Material Sciences Center, Philipps-University of Marburg, Renthof 5, 35032 Marburg, Germany. limei.klar@physik.uni-marburg.de.

ABSTRACT
Transients of Mn internal 3d5 luminescence in ZnS/Mn nanowires are strongly non-exponential. This non-exponential decay arises from an excitation transfer from the Mn ions to so-called killer centers, i.e., non-radiative defects in the nanostructures and is strongly related to the interplay of the characteristic length scales of the sample such as the spatial extensions, the distance between killer centers, and the distance between Mn ions. The transients of the Mn-related luminescence can be quantitatively described on the basis of a modified Förster model accounting for reduced dimensionality. Here, we confirm this modified Förster model by varying the number of killer centers systematically. Additional defects were introduced into the ZnS/Mn nanowire samples by irradiation with neon ions and by varying the Mn implantation or the annealing temperature. The temporal behavior of the internal Mn2+ (3d5) luminescence is recorded on a time scale covering almost four orders of magnitude. A correlation between defect concentration and decay behavior of the internal Mn2+ (3d5) luminescence is established and the energy transfer processes in the system of localized Mn ions and the killer centers within ZnS/Mn nanostructures is confirmed. If the excitation transfer between Mn ions and killer centers as well as migration effects between Mn ions are accounted for, and the correct effective dimensionality of the system is used in the model, one is able to describe the decay curves of ZnS/Mn nanostructures in the entire time window.

No MeSH data available.


Related in: MedlinePlus