Dynamical processes on relaxed excited states in NH₄Cl:Tl⁺ single crystals

Abstract

We have investigated the temperature dependence of temporal behaviors of the A X and A T luminescence bands in NH 4 Cl:Tl + single crystals under an ArF excimer laser excitation. The time-resolved A X luminescence spectra reveal the existence of two luminescence bands which are attributed to the radiative transitions from the relaxed 3 T 1u and 3 A 1u states, respectively. The slow decay of the luminescence due to the transition from the 3 A 1u state in the A X band becomes fast with increasing temperature from 16 K to 27 K. Then, the A T band exhibits a temporal rise reflecting the non-radiative transition from the A X to A T minima on the adiabatic potential energy surface for the 3 A 1u state. The temperature dependence of the slow decay time of the A X band is analyzed by using the WKB method considering the non-radiative transitions from vibrational energy levels in the adiabatic potential well. As a results, the temperature dependence can be fitted by taking the TA phonon energy of the NH 4 Cl bulk crystal as the separation energy between the vibrational energy levels.

Optically stimulated luminescence properties of Tl-doped NH4Cl transparent ceramics fabricated by SPS method

“…The spectrum shape of the longer wavelength is similar to that of the NH 4 Cl fine powder in previous reports; therefore, the peaks at around 1300, 1600, 2200, and 2700 nm can be assigned to the combination of N-H stretching and N-H bending (A), the first overtone stretch of N-H bonds (B), the combination of NH 4 + asymmetric stretching and NH 4 + bending (C), and O-H stretching (D), respectively [41][42][43][44]. Compared with the previous report of the Tldoped NH 4 Cl single crystals, the peak at around 240 nm was attributed to the 1 S 0 → 3 P 1 transitions of Tl + [36][37][38].…”

“…Second, Tl-doped ammonium salts such as (NH 4 ) 2 SiF 6 and NH 4 Br were reported to exhibit a high OSL sensitivity to fast neutrons [35]; thus, we expected that Tl-doped NH 4 Cl would also exhibit effective OSL properties. In addition, although there have been some reports of optical properties of Tl-doped NH 4 Cl [36][37][38], the OSL properties have not been studied yet. For the above reasons, we fabricated Tl-doped NH 4 Cl transparent ceramics using SPS and evaluated the OSL properties.…”

Long‐Lived Photoluminescence in Amorphous Si–O–C(–H) Ceramics Derived from Polysiloxanes

“…The window of the cell was made of quartz, and the pressure was monitored using a Pirani gauge (GP‐2A with a probe of WP‐05; ULVAC Inc., Chigasaki, Japan). The details of the time‐resolved analysis have been described in previous reports …”

Decay kinetics of the luminescence of Ag– centers doped in alkali halide crystals

“…This means that the A′ luminescence mainly occurs from level 1 at low temperature and does from level 2 at higher temperatures. Under these conditions, the temperature dependence of the decay time constant can be expressed as [16,20,28,39] …”