Thermal and microstructural analysis of Cu(II) 2,2 0 -dihydroxy azobenzene and thin films deposition by MAPLE technique C. Constantinescu • E. Morı ˆntale • Ana Emandi • Maria Dinescu • P. Rotaru Received: 2 June 2010 / Accepted: 16 July 2010 / Published online: 9 August 2010 Ó Akade ´miai Kiado ´, Budapest, Hungary 2010 Abstract A newly synthesized copper-complex exhibit- ing nonlinear optical properties, crystalline nature, and generating interest as a material for non-linear optical applications was investigated. As thermal stability studies are indispensable before attempting any laser-assisted processing experiments, the thermal behavior of 2,2 0 - dihydroxy azobenzene with Cu 2? cations that are found to organize themselves as non-central symmetric crystallites, was investigated. The thin films were deposited on silicon substrates by matrix-assisted pulsed laser evaporation using a Nd:YAG laser working at 266 and 355 nm. Thermal analysis of the bulk compound indicates a higher thermal stability in argon flow when compared to the air atmo- sphere; as well, since, the adhesion of the compound onto the substrate enhances the bonding, the thermal stability of the Cu complex increases. Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, spectroscopic ellipsometry, and ultraviolet– visible spectroscopy investigations were also performed. Keywords Cu complex Á MAPLE Á Thermal analysis Á Thin film Introduction Metal-organic complex compounds with azobenzene rings are important materials of real economic interest, with direct applications as thin films for non-linear optics, optical storage, or for various sensors [1–4]. Laser processing of such complex materials represents a solution for obtaining smooth, continuous, and chemically intact thin films. Unfortunately, conventional pulsed laser deposition (PLD)—which has been used as a successful technique for fabricating inorganic thin films of controlled thickness and composition [5]—cannot be applied to most organic and other soft materials, since irradiation by UV light induces substantial decomposition of the target molecules [6–10]. Thin films of organometallic and coordinative compounds, polymers, bio- and hybrid metal-organic materials can be fabricated employing an alternative technique, known as MAPLE (matrix assisted pulsed laser evaporation) [11–13]. This recent technique is a versatile way of depositing such fragile compounds on various surfaces and controlling shape and thickness at nanometer scale (10–500 nm) [14– 28]. MAPLE involves dissolving or suspending the com- plex material (0.1–2 wt%) in a volatile solvent (matrix), freezing the mixture to create a solid target, and employing a low-fluence pulsed laser to displace the target and pul- verize it into vacuum chamber. When the matrix is irradi- ated by laser radiation, the solvent evaporates, whereas the guest molecules are collected onto a substrate. A successful film deposition by MAPLE technique requires a matrix with an absorption band in the range of the working wavelength of the laser and a relatively low absorption by the guest material. It is also important to consider that possible pho- tochemical reactions between the matrix and guest materi- als should be avoided or considerably reduced, but these requirements are usually difficult to fulfill completely. C. Constantinescu Á M. Dinescu PPAM-Lasers Department, INFLPR-National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor blvd., Magurele, 077125 Bucharest, Romania E. Morı ˆntale Á P. Rotaru (&) Faculty of Physics, University of Craiova, 13 AI Cuza Street, 200585 Craiova, Dolj, Romania e-mail: protaru@central.ucv.ro; petrerotaru@yahoo.com A. Emandi Department of Inorganic Chemistry, Faculty of Chemistry, University of Bucharest, 23 Dumbrava Rosie Street, 010184 Bucharest, Romania 123 J Therm Anal Calorim (2011) 104:707–716 DOI 10.1007/s10973-010-0971-x