Single crystal WS2 for mechanical exfoliation. The crystal measure a minimum of 3mm x 3mm in lateral dimensions.
The Raman spectrum of bulk WS2 shows 2 prominent peaks: the in-plane E2gmode at ~352cm-1 and the out-of-plane A1gmode at ~420cm-1. This peaks are characteristic for hexagonally crystallized WS2. When exfoliated in monolayer, the two peaks come closer and there is a strong photoluminescence around 1.9eV.