Characteristics of an organic nonlinear optical material urea l-malic acid film

Urea l-malic acid (ULMA) is one of the derivatives of urea. ULMA keeps the nonlinear optical properties and broad transparency range of urea with greatly reduced hygroscopicity. ULMA film (2 μm) was prepared with physical vapour deposition (PVD) method. XRD and FTIR measurements show that the film and the ULMA powder have the same composition and crystal structure. Furthermore, the film keeps the nonlinear properties of the ULMA crystal.