Photoinduced polymerization and relaxation in liquid sulphur

Sakaguchi, Yoshifumi; Tamura, Keiko

doi:10.1088/0953-8984/7/25/005

Cited by 20 publications

(17 citation statements)

References 26 publications

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“…42 In this case, a high-viscous layer can be created on the surface by photo-induced polymerization in the system. 43 The appearance of the layer may cause new interaction with underneath low-viscous liquid composed of S 8 rings at the interface which could result in such wrinkle patterns formation. Those examples indicate that the present wrinkle patterns should be formed by specific conditions at the interface.…”

Section: -8mentioning

confidence: 99%

Silver photo-diffusion and photo-induced macroscopic surface deformation of Ge33S67/Ag/Si substrate

Sakaguchi

Asaoka

Uozumi

et al. 2016

Journal of Applied Physics

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Ge-chalcogenide films show various photo-induced changes, and silver photo-diffusion is one of them which attracts lots of interest. In this paper, we report how silver and Ge-chalcogenide layers in Ge 33 S 67 /Ag/Si substrate stacks change under light exposure in the depth by measuring timeresolved neutron reflectivity. It was found from the measurement that Ag ions diffuse all over the matrix Ge 33 S 67 layer once Ag dissolves into the layer. We also found that the surface was macroscopically deformed by the extended light exposure. Its structural origin was investigated by a scanning electron microscopy. Published by AIP Publishing. [http://dx

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Section: -8mentioning

confidence: 99%

Silver photo-diffusion and photo-induced macroscopic surface deformation of Ge33S67/Ag/Si substrate

Sakaguchi

Asaoka

Uozumi

et al. 2016

Journal of Applied Physics

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“…On the experimental side, transient absorption experiments in liquid S revealed that polymerization of S 8 molecules takes place by bandgap illumination with a pulsed laser. 8 The relaxation processes through which photo-polymerized molecules return back to equilibrium was also studied in detail. 8 Ab initio molecular dynamics simulations followed experimental observation providing evidence for the photoinduced bond scission of isolated S 8 rings and partial polymerization in the liquid phase.…”

mentioning

confidence: 99%

“…8 The relaxation processes through which photo-polymerized molecules return back to equilibrium was also studied in detail. 8 Ab initio molecular dynamics simulations followed experimental observation providing evidence for the photoinduced bond scission of isolated S 8 rings and partial polymerization in the liquid phase. 9 Apart form these works on PiP in elemental liquid S, no other study is known about this effect in sulfide glasses.…”

mentioning

confidence: 99%

Colossal photostructural changes in chalcogenide glasses: Athermal photoinduced polymerization in AsxS100−x bulk glasses revealed by near-bandgap Raman scattering

Kyriazis

Yannopoulos

2009

Applied Physics Letters

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Near-bandgap Raman scattering was used to induce and study photostructural changes in As x S 100-x bulk glasses (5≤x As ≤40) revealing a new photoinduced polymerization effect. Raman spectra were recorded also in off-resonant conditions allowing for a detailed comparison between the "equilibrium" glass structure and the metastable one induced by illumination. It is shown that in S-rich glasses structural changes involve the athermal scission of S 8 rings and their polymerization to S n chains. The fraction of bonds involved in this effect is surprisingly high, being one order of magnitude higher than the corresponding fractions reported up to now in photostructural studies in chalcogenide glasses.

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“…The application of optical spectroscopy techniques is critical in liquid Sulphur, since its absorption spectrum is considerably different [3,4] between the monomeric and the polymerdominated phase. Specifically, undesired absorption and photo-induced changes occur when studying the liquid with visible laser wavelengths on increasing temperature above T λ [16]. To overcome these problems, we developed a new technique employing a near infrared radiation as probing field (λ=1064 nm), namely Infra-Red Photon Correlation Spectroscopy (IRPCS).…”

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confidence: 99%

Origin of theλTransition in Liquid Sulfur

et al. 2007

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Developing a novel experimental technique, we applied photon correlation spectroscopy using infrared radiation in liquid Sulphur around T λ , i.e. in the temperature range where an abrupt increase in viscosity by four orders of magnitude is observed upon heating within few degrees. This allowed us -overcoming photo-induced and absorption effects at visible wavelengths -to reveal a chain relaxation process with characteristic time in the ms range. These results do rehabilitate the validity of the Maxwell relation in Sulphur from an apparent failure, allowing rationalizing the mechanical and thermodynamic behavior of this system within a viscoelastic scenario. PACS numbers: 62.60.+v,64.70.Ja,62.10.+s, Common wisdom holds that liquids become less viscous as the temperature is raised. On a microscopic ground, indeed, viscosity can be regarded as arising from continual brushing of molecules which are close to each other. On increasing temperatures the more vigorous thermal motion of the molecules is expected to render such mutual friction progressively less effective. This naive description provides a qualitative interpretation of the decrease in viscosity normally observed in almost all substances as the temperature increases. There exist, however, a few remarkable exceptions exhibiting complex behavior, which can be regarded as extreme examples of how critically viscosity depends upon molecular interactions. Specifically, there are ranges of temperatures in which the viscosity of Sulphur exhibits anomalous temperature dependence. In the liquid state, just above melting (T m =119 o C), eight-membered rings (S8) are the most abundant species, and the viscosity slightly decreases with temperature as normally expected, reaching values as low as 0.01 Pa·s at T = 157 o C. Further increase of temperature causes a dramatic increase of viscosity [1], accompanied by gross changes in optical [2,3,4] and thermodynamic [5,6] properties, which, at T ≈185 o C, reaches a maximum value of 100 Pa·s. Beyond this temperature, a gradual viscosity decrease is observed. Although this phenomenon, known as λ-transition (T λ = 159 o C), has been tackled for more than 150 years, its comprehension is still far from being reached: to rationalize this puzzling temperature dependence of viscosity, indeed, a liquid-liquid transition from a monomeric (i.e. a S8 rings liquid) to a polymeric phase has been invoked [7,8]. The temperature dependence of the mass fraction of S atoms participating in the polymeric component turns out to be a central parameter for extracting information on many thermodynamic aspects of the λ-transition [9,10]. This phenomenon has been classified as a living polymerization [11] transition that essentially involves two steps, the initiation (formation of diradicals through opening of S8 rings) and propagation (concatenation of species to form long polymeric chains). Thermo-chemical models were developed in the past [12,13,14] to relate the transport properties of liquid sulphur to the underlying polymerization phenomenon. T...

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Photoinduced polymerization and relaxation in liquid sulphur

Cited by 20 publications

References 26 publications

Silver photo-diffusion and photo-induced macroscopic surface deformation of Ge33S67/Ag/Si substrate

Silver photo-diffusion and photo-induced macroscopic surface deformation of Ge33S67/Ag/Si substrate

Colossal photostructural changes in chalcogenide glasses: Athermal photoinduced polymerization in AsxS100−x bulk glasses revealed by near-bandgap Raman scattering

Origin of theλTransition in Liquid Sulfur

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