The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Further information on publisher's website:http://dx.doi.org/10.1039/c1an15722aPublisher's copyright statement:Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractTotal internal reflection (TIR) Raman spectroscopy is an experimentally straightforward, surface-sensitive technique for obtaining chemically specific spectroscopic information from a region within approximately 100-200 nm of a surface. While TIR Raman spectroscopy has long been overshadowed by surface-enhanced Raman scattering, with modern instrumentation TIR Raman spectra can be acquired from sub-nm thick films in only a few seconds. In this review, we describe the physical basis of TIR Raman spectroscopy and illustrate the performance of the technique in the diverse fields of surfactant adsorption, liquid crystals, lubrication, polymer films and biological interfaces, including both macroscopic structures such as the surfaces of leaves, and microscopic structures such as lipid bilayers. Progress, and challenges, in using TIR Raman to obtain depth profiles with sub-diffraction resolution are described.

Total internal reflection (TIR) spectroscopy is a widely used technique to study soft matter at interfaces. This tutorial review aims to provide researchers with an overview of the principles, experimental design and applications of TIR spectroscopy to enable them to understand how this class of techniques might be used in their research. It also highlights limitations and pitfalls of TIR techniques, which will assist readers in critically analysing the literature. Techniques covered include attenuated total reflection infrared spectroscopy (ATR-IR), TIR fluorescence, TIR Raman scattering and cavity-enhanced techniques. Other related techniques are briefly described.

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractTotal internal reflection (TIR) Raman spectroscopy has been used to study the kinetics of adsorption, desorption and displacement of mixed surfactant systems at the silica-water interface.The limited penetration depth of the evanescent wave provides surface sensitivity while the chemical sensitivity of Raman scattering permits the determination of the time-dependent composition of the adsorbed film. Principal component analysis is used to deconvolute the Raman spectra with a time resolution of 2 s and a precision of 5% of a monolayer. Both equilibrium and kinetic measurements are presented for the cetyltrimethylammonium bromide (CTAB)/Triton X-100 system over a range of concentrations and compositions. For a total concentration of 2 mM, the adsorption isotherm shows strong synergistic behavior with the addition of small amounts of CTAB (~2% of the total surfactant) doubling the adsorbed amount of Triton X-100. This synergism has a marked influence on the kinetics: for example, when Triton X-100 replaces CTAB the Triton X-100 surface excess overshoots its equilibrium value and returns only very slowly to equilibrium. For systems above the cmc, the repartitioning of surfactant between micelles and monomers results in unexpected behavior during exchange or rinsing of mixed surfactant solutions. For example, during rinsing the more rapid diffusion of CTAB away from the surface leads to a local increase in the monomer concentration of Triton X-100 resulting in a temporary spike in the Triton X-100 surface excess. Displacement kinetics of CTAB by TX-100 and vice versa are generally slower than the adsorption or desorption of the pure surfactants, but cover a wide range of kinetic timescales depending on the details of the compositions and concentrations of the initial and final solutions.

Total internal reflection Raman spectroscopy provides a sensitive probe of surfactants adsorbed at an interface. A visible laser passes through a silica hemisphere and reflects off the flat silica–water interface. An evanescent wave probes ∼100 nm of solution below the surface, and the Raman scattering from this region provides chemically specific information on the molecules present. Here we look at both equilibrium and kinetic aspects of the adsorption of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the nonionic surfactant Triton X-100 in single-component systems. We use the well-defined wall jet geometry to provide known hydrodynamics for the adsorption process. The well-defined hydrodynamics allows us to model the mass transport of surfactant to the surface which is coupled with a kinetic model consistent with the Frumkin isotherm to produce a complete model of the adsorption process. The fit between this model and the experimental results provides insight into the interactions on the surface.

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. A methodology based on time-resolved, phase-sensitive second harmonic generation (SHG) for probing the excited state dynamics of species at interfaces is presented. It is based on an interference measurement between the SHG from the sample and a local oscillator generated at a reference together with a lock-in measurement to remove the large constant offset from the interference. The technique is characterized by measuring the phase and excited state dynamics of the dye malachite green at the water/air interface. The key attributes of the technique are that the observed signal is directly proportional to sample concentration, in contrast to the quadratic dependence from non-phase sensitive SHG, and that the real and imaginary parts of the 2nd order non-linear susceptibility can be determined independently. We show that the method is highly sensitive and can provide high quality excited state dynamics in short data acquisition times. C 2015 AIP Publishing LLC.[http://dx

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract TIR Raman spectroscopy has been used to study the adsorption of surfactants onto cellulose. The cellulose was prepared by Langmuir-Blodgett deposition of trimethylsilylcellulose onto silica followed by removal of the trimethylsilyl groups with acid to generate a hydrophilic surface. The reaction was followed in situ with Raman spectroscopy, revealing a two-step hydrolysis. Adsorption isotherms of hexadecyltrimethylammonium bromide (CTAB) and Triton X-100(TX-100) on hydrophilic cellulose were obtained by TIR Raman scattering under quasi-equilibrium conditions where the bulk concentration was slowly but continuously varied. The isotherms of both surfactants are almost linear, in contrast to the isotherms on hydrophilic silica. The CTAB isotherm shows hysteresis depending on whether the concentration of the surfactant is increasing or decreasing due to a slow adsorption region. A mixture of TX-100 and CTAB shows ideal adsorption, in contrast to adsorption of the same mixture on silica where there is a strong cooperative interaction at low CTAB surface coverage.