Thin Films of Nanocrystalline Fe(pz)[Pt(CN)4] Deposited by Resonant Matrix-Assisted Pulsed Laser Evaporation.

Dominik Maskowicz,Armin Kleibert,Maria Gazda,Rafał Jendrzejewski,Carlos A F Vaz,Yann Garcia,Jakub Karczewski,Mirosław Sawczak,Paweł Niedziałkowski,Wioletta Kopeć

doi:10.3390/ma14237135

Abstract

Prior studies of the thin film deposition of the metal-organic compound of Fe(pz)Pt[CN]4 (pz = pyrazine) using the matrix-assisted pulsed laser evaporation (MAPLE) method, provided evidence for laser-induced decomposition of the molecular structure resulting in a significant downshift of the spin transition temperature. In this work we report new results obtained with a tunable pulsed laser, adjusted to water resonance absorption band with a maximum at 3080 nm, instead of 1064 nm laser, to overcome limitations related to laser–target interactions. Using this approach, we obtain uniform and functional thin films of Fe(pz)Pt[CN]4 nanoparticles with an average thickness of 135 nm on Si and/or glass substrates. X-ray diffraction measurements show the crystalline structure of the film identical to that of the reference material. The temperature-dependent Raman spectroscopy indicates the spin transition in the temperature range of 275 to 290 K with 15 ± 3 K hysteresis. This result is confirmed by UV-Vis spectroscopy revealing an absorption band shift from 492 to 550 nm related to metal-to-ligand-charge-transfer (MLCT) for high and low spin states, respectively. Spin crossover is also observed with X-ray absorption spectroscopy, but due to soft X-ray-induced excited spin state trapping (SOXIESST) the transition is not complete and shifted towards lower temperatures.

Highlights

IntroductionSpin crossover (SCO) materials are widely investigated due to their ability to switch their spin state upon the influence of external conditions, such as temperature [1], light irradiation [2], and pressure [3]
Confirmed that the nanocrystals are in the form of plates with average dimensions of SEM analysis confirmed that the nanocrystals are in the form of plates with average di143 × 143 × 21 nm3
The orarrangement of the crystals on the surface was confirmed by the X-ray diffraction (XRD) analysis, in derly arrangement of the crystals on the surface was confirmed by the XRD analysis, which enhanced reflections from selected crystal planes were observed

Summary

Introduction

Spin crossover (SCO) materials are widely investigated due to their ability to switch their spin state upon the influence of external conditions, such as temperature [1], light irradiation [2], and pressure [3] Various proposed applications, such as in electronics, memory devices, molecular switches, or sensors [4], require nanoscale size and functionality at room temperature. The solvent used in this process, called a matrix, serves as a protector (absorbing the majority of laser energy) and as a carrier (during ablation, dispersed nanocrystals are carried with the matrix droplets towards substrate) [13,14,15] The first of these roles is the major advantage of the MAPLE method as it prevents significant damage of SCO nanocrystals, which are highly susceptible to chemical decomposition, structural collapse, and deterioration of the spin-crossover properties

Methods

Results

Conclusion