Photoswitching of the spin crossover polymeric material [Fe(Htrz)2(trz)](BF4) under continuous laser irradiation in a Raman scattering experiment

Abstract

Photoswitching of the [Fe(Htrz) 2 (trz)](BF 4) spin crossover polymeric material has been investigated by means of confocal Raman spectroscopy upon continuous laser irradiation outside and inside its thermal hysteresis loop. In both cases, the evolution of HS and LS Raman marker bands show that light excitation can trigger the LS to HS transition, but the long-lived HS state can be populated only within the hysteresis loop. Local sample heating can explain this light-induced effect leading to a narrowing of the thermal hysteresis loop for laser intensities higher than 0.02 mW/lm 2 , in strong accordance with previous time-resolved pump-probe experiments on similar materials.

Reversible Control by Light of the High‐Spin Low‐Spin Elastic Interface inside the Bistable Region of a Robust Spin‐Transition Single Crystal

“…Note that bidirectional photo-switching inside the thermal hysteresis using pulsed nanosecond laser excitation was first reported for the SC sample [Fe(pyrazine)Pt(CN) 4 ], [35] and later on other type of SC solids, [36] using Raman spectroscopy.W hile there is no doubt about the physical mechanism of the LS to HS photo-transformation, the reverse process inside the hysteresis is still disputable.The reverse process feeds into the healthy debate,w hich was reignited recently by photocalorimetric measurements [37] under pulse laser on the [Fe-(pyrazine)Pt(CN) 4 ]S Cs ample,l eading to ac ontroversy.O f course,t hese results should be confirmed by other investigations,capitalizing as in Ref. [37],onthe remarkable advances of the last two decades,i nt he chemical synthesis of high quality single crystals, [3,[38][39][40][41] combined with technological advances in experimental techniques (ultra-fast photo-crystallography, [42][43][44] time-resolved optical experiments [27,45] ), and methods of visualization at the nanoscale. [46] In conclusion, we have experimentally shown that modulation of aw eak intensity of light at as uitable frequency could reversibly control the spin transition in the thermal hysteresis interval.…”

Spin Transition Kinetics in the Salt [H2N(CH3)2]6[Fe3(L)6(H2O)6] (L = 4-(1,2,4-triazol-4-yl)ethanedisulfonate)

“…Fe(II) complexes represent the most numerous and remarkable family of SCO materials, matching all these requirements [7,8]. Several materials exhibit room temperature switchability [9] and ultra-fast light controlled responses [10][11][12][13][14]. In addition to their intrinsic properties, these SCO materials can be also used as probes to switch a second property in a hybrid multicomponent system [15,16].…”

Reversible Control by Light of the High‐Spin Low‐Spin Elastic Interface inside the Bistable Region of a Robust Spin‐Transition Single Crystal

“…Of course, these results should be confirmed by other investigations, capitalizing as in Ref. , on the remarkable advances of the last two decades, in the chemical synthesis of high quality single crystals, combined with technological advances in experimental techniques (ultra‐fast photo‐crystallography, time‐resolved optical experiments), and methods of visualization at the nanoscale …”