The CL and PL characteristic of different scale CsI:Na crystals

TL;DR

This study compares the luminescence properties of CsI:Na crystals of different sizes under photoluminescence and cathodoluminescence, revealing size-dependent emission behaviors and the influence of surface defects.

Contribution

It provides new insights into how crystal size affects luminescence characteristics and the role of surface defects in CsI:Na crystals.

Findings

Nano-scale CsI:Na emits at 420nm under PL, but shows different bands under CL.

Surface defects increase as crystal size decreases, reducing Na-related luminescence.

CsI:Tl emission is unaffected by crystal size under the same conditions.

Abstract

We investigate the luminescence characteristic of different scale CsI:Na crystals excited via photoluminescence(PL) and cathodoluminescence (CL). The CsI:Na crystals are processed to three samples with different diameter, decreasing from micro-scale to nano-scale. It is found that the nano-scale CsI:Na crystal emits 420nm luminescence by PL, while its emission band is at 315nm and 605nm by CL. The reason for this phenomenon relates to the energy and density of incident particles, and the diameter of CsI:Na crystal. When crystal diameter decreases to nano-scale, the number of surface defects relatively increases, leading to the Na-relative luminescence decreasing. In addition, we have also investigated the CsI:Tl crystal with the same experiment condition. The result indicates that the emission almost has nothing to do with the crystal diameter.