Second-Harmonic Scattering Can Probe Hydration and Specific Ion Effects in Clay Particles

Abstract

We report Montmorillonite (MMT) particles organization in aqueous solution using polarization resolved second harmonic scattering (SHS). This technique can probe specifically the organization of water in this system. The effect of the colloidal stability of the particle and the nature of the interlayer cations on the SHS Intensity is highlighted. The interlayer hydration has been probed and changes with the order Mg 2+ > Ca 2+ > Li + , Na + , K + > Cs +. Real time SHS evolutions during cesium exchange have been monitored, and different pathways are discussed in regards with the experimental results.

PySHS: Python Open Source Software for Second Harmonic Scattering

“…where (2) χ ' ◊ ÷÷÷÷÷÷ is the surface second order nonlinear susceptibility of the sphere. Using the same formalism as above, The SHS ◊ ÷÷÷÷÷ (17) The SPHERE program in the PySHS package takes the surface second order nonlinear susceptibility and the radius of the sphere as input parameters and computes the same quantities as defined above in eqs 11−14.…”

“…Nonlinear light scattering methods and in particular second harmonic scattering (SHS) has been widely used to investigate solvation, hydration, and correlation − of molecule in solution, self-assembly, , interfacial properties of small particles, − droplets in liquids, , biological membranes, − or structuration of materials. − Numerous models − have been developed to interpret experimental data and in particular angular distribution and polarization dependence of the second harmonic scattered light. The understanding of such variation allows the recovery of important properties about the symmetry, organization, and/or correlation − of the nano-objects probed.…”

PySHS : A Python Open Source Software For Second Harmonic Scattering

“…PySHS package offers the possibility to compute the SHS intensity of homogeneous spheres in solution. To perform this calculation, an effective nonlinear susceptibility Γ (2) ⃡⃗⃗⃗⃗⃗ is introduced as proposed in this work 25 , it represents the nonlinear response of the entire sphere surface:…”

“…⃡⃗⃗⃗⃗⃗⃗ . 𝑒 𝑖Δ𝑘 ⃗⃗⃗⃗⃗ .𝑟 𝑑𝑟 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑝ℎ𝑒𝑟𝑒 (16) where 𝜒 (2) ⃡⃗⃗⃗⃗⃗⃗ is the surface second order nonlinear susceptibility of the sphere. Using the same formalism as above, The SHS intensity is expressed with the same equation ( 3) where 𝛽 𝑒𝑓𝑓 is now expressed as:…”

“…Nonlinear light scattering methods and in particular Second Harmonic Scattering (SHS) has been widely used to investigate solvation 1 , hydration 2 and correlation [3][4][5][6][7] of molecule in solution 8 , self assembly [9][10] , interfacial properties of small particles [11][12][13][14] , droplets in liquids [15][16] , biological membranes [17][18][19][20][21] or structuration of materials [22][23][24] . Numerous models [25][26][27][28][29][30] have been developed to interpret experimental data and in particular angular distribution and polarization dependence of the second harmonic scattered light.…”