Coexistence of metastable nitric acid dihydrates: A molecular level contribution to understanding the formation of polar stratospheric clouds crystals

This study provides a detailed knowledge of the formation pathways for gas-phase di and trihydrates of the nitric acid - key components of the ice crystals formed in polar stratospheric clouds. The present study leads us to conclude that nitric acid crystals under stratospheric conditions are formed mainly from β-NAD and β-NAT.