Nanosecond spectroscopy of Ce‐doped CaGa
            <sub>2</sub>
            S
            <sub>4</sub>

Takayama, Katsuhiko; Tanaka, Kunihiko; Uchiki, Hisao; Hidaka, Chiharu; Takizawa, Takeo

doi:10.1002/pssc.200669594

Cited by 2 publications

(2 citation statements)

References 8 publications

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“…However, it has been reported from the results of nanosecond pump-probe spectroscopy that the excited state absorption (ESA) associated with the transition from the 5d 1 state to the conduction band of CaGa 2 S 4 host is very strong and inhibits light amplification [5,6]. In the report some unresolved issue remained that the decay times of the photoluminescence (PL) by the 5d 1 -4f transition (∼29 ns) and the ESA from the 5d 1 state (∼25 ns) did not agree each other, suggesting that the initial state is different for the PL and ESA processes.…”

Section: Introduction Cementioning

confidence: 99%

Site‐dependent excited state absorption in Ce‐doped CaGa2S4 single crystal

Uchiki

Honma

Tanaka

et al. 2013

Phys. Status Solidi C

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Excited state absorption (ESA) by Ce3+ ions in the 5d1 lowest excited state in Ce‐doped CaGa2S4 single crystal was investigated by nanosecond two‐pulse pump‐CW probe spectroscopy. The first pump pulse of 425 nm excited the 4f ground state electron to the 5d1 first excited state and the second pump pulse of 589 nm was introduced at 13 ns after the first pump in order to selectively excite the 5d1 state. Transient intensity change of the CW probe of a diode laser of 780 nm was observed. Temporal behavior of photoluminescence intensity by the 5d1 to 4f state transition was also observed under excitation of the same two‐pulse pump.The experimental results can be explained by the model of site‐dependent excited state absorption. The photoluminescence is generated from the 5d1 states of Ce3+ at two sites with different decay time, whereas the excited state absorption takes place mainly from Ce3+ at one site as well as metastable Ce2+. The model predicts that optical gain by the 5d1 to 4f transition can be achieved by Ce3+ at the other site if the populations at both the 5d1 state of Ce3+ at the site resulting in ESA and Ce2+ can be bleached by simultaneous secondary optical pumping with an IR (e.g. Nd:YAG) laser. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Introduction Cementioning

confidence: 99%

Site‐dependent excited state absorption in Ce‐doped CaGa2S4 single crystal

Uchiki

Honma

Tanaka

et al. 2013

Phys. Status Solidi C

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“…These processes have been well investigated in Ce 3+ -doped CaGa 2 S 4 by using ultraviolet (UV) and visible (VIS) light [3][4][5][6]. The absorption band of Ce 3+ ions locates at 2.92 eV below the fundamental absorption edge of host CaGa 2 S 4 .…”

Section: Introductionmentioning

confidence: 99%

Excitation processes of trivalent cerium ions in calcium thiogallate crystals by hot photocarriers

Kitaura

Ohnishi

Sasaki

et al. 2010

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Excitation spectra for the 5d → 4f emission of Ce 3+ ions in CaGa 2 S 4 crystals have been measured at 300 K by using vacuum ultraviolet (VUV) photons, together with reflectivity and absorption-edge spectra. X-ray photoelectron spectroscopy (XPS) experiment has also been performed in order to clarify the contribution of shallow core states to the excitation and reflectivity spectra. Furthermore, cluster calculation by a relativistic discrete variational X (DV-X method has been carried out to elucidate the optical transitions resulting in the creation of multiple e-h pairs in CaGa 2 S 4 . The excitation processes of Ce 3+ ions in CaGa 2 S 4 by hot photocarriers are discussed on the basis of the electronic structure determined from the experiments and calculation. IntroductionLuminescence properties of inorganic phosphors have been studied toward applications for flat panel display and solid-state lighting. Development of inorganic phosphor devices is achieved through continuous investigation of phosphor materials. Since fundamental researches were focused on ternary compounds such as II-III-VI group for the past 10 years [1], some bright phosphors were synthesized using alkaline-earth thiogallates and thioalminates as host materials. For example, Eu 2+ -activated BaAl 2 S 4 attracts attention as a high-luminance blue-emitting phosphor which satisfies requirements for full colour display [2]. Actually, a full colour flat panel display using this phosphor was demonstrated. Therefore, it is supposed that rare-earth-activated alkaline-earth thiogallates and thioalminates are key materials for the designing of inorganic phosphor devices.Investigations of emission and excitation processes are of great importance in phosphor materials. These processes have been well investigated in Ce 3+ -doped CaGa 2 S 4 by using ultraviolet (UV) and visible (VIS) light [3][4][5][6]. The absorption band of Ce 3+ ions locates at 2.92 eV below the fundamental absorption edge of host CaGa 2 S 4 . Two emission bands are observed at 2.65 and 2.40 eV under photoexcitation in the Ce 3+ absorption band, and are attributed to the electronic transitions from the 5d state to the 4f state in Ce 3+ ions. On the other hand, the emission and excitation processes of Ce 3+ ions have not yet been investigated under photoexcitation in the fundamental absorption region. These data are essentially required to know how hot conduction electrons interact with luminescence ions or host materials. Such information would be surely useful for understanding of electroluminescence (EL) and

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Nanosecond spectroscopy of Ce‐doped CaGa ₂ S ₄

Cited by 2 publications

References 8 publications

Site‐dependent excited state absorption in Ce‐doped CaGa2S4 single crystal

Site‐dependent excited state absorption in Ce‐doped CaGa2S4 single crystal

Excitation processes of trivalent cerium ions in calcium thiogallate crystals by hot photocarriers

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Nanosecond spectroscopy of Ce‐doped CaGa 2 S 4

Cited by 2 publications

References 8 publications

Site‐dependent excited state absorption in Ce‐doped CaGa2S4 single crystal

Site‐dependent excited state absorption in Ce‐doped CaGa2S4 single crystal

Excitation processes of trivalent cerium ions in calcium thiogallate crystals by hot photocarriers

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Nanosecond spectroscopy of Ce‐doped CaGa ₂ S ₄