Supplementary information

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1 Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics. This journal is the wner Societies 26 Supplementary information Structure and dynamics of water molecules confined in triglyceride oils Carien. C. M. Groot, Krassimir P. Velikov and Huib J. akker This supplementary information contains several figures that illustrate observations made in the main article. bs [D/mm] bs [D/mm] C bs [D/mm] 2 4ml/l.5 2ml/l ml/l 2ml/l ml/l 2.5ml/l ml/l ml wavenumbers [cm - ] D bs [D/mm.cm - ] E bs [D/mm.cm - ] F bs [D/mm.cm - ] water concentration [ml/l] Fig. S Linear absorption spectra of different amounts of isotopically diluted water (:9 :) dissolved in (), () and (C), and the integrated D stretch absorption as a function of water concentration for each triglyceride (D F). The spectra are corrected for the response of in triglyceride at the same water concentrations. The integrated D stretch absorption increases gradually, until the saturation limit is reached and adding more water does not increase the absorption further. For un solutions, the integrated absorption can be related to the water concentration by an empirical second order polynomial fit (solid lines). The water concentration at which the fit reaches the integrated D stretch absorption of a solution (dotted lines), indicated with arrows, is then an estimate for the water concentration of a solution. This is 57±2 ml/l, 6.8± ml/l and 3.4± ml/l for, and respectively, which corresponds to molar water to lipid ratios of about :.7, :9, and :.

2 Table Extracted parameters from Gaussian fit to the linear absorption spectra of water dissolved in, and. The parameters include the amplitude, center frequency ω and full width at half maximum FWHM. The subscripts refer to the different bands: the H bonded D stretch () and the free D stretch (Free) from water molecules that form a single strong H bond to the triglyceride, and the D stretch from water molecules that form two weaker H bonds to the triglyceride (D), subdivided into symmetric (D,s) and antisymmetric (D,a) D stretch vibrational bands. For water in, an additional Gaussian band is added to describe the overtone of the bend vibration (ver). % : % : % : [md] D [md] Free [md] ω [cm ] ω D [cm ] ω Free [cm ] FWHM [cm ] FWHM D [cm ] FWHM Free [cm ] [md] D,s [md] D,a [md] Free [md] ver [md] 32 ω [cm ] ω D,s [cm ] ω D,a [cm ] ω Free [cm ] ω ver [cm ] 2394 FWHM [cm ] FWHM D,s [cm ] FWHM D,a [cm ] FWHM Free [cm ] FWHM ver [cm ].7 [md] D,s [md] D,a [md] Free [md] ver [md].3 ω [cm ] ω D,s [cm ] ω D,a [cm ] ω Free [cm ] ω ver [cm ] 3265 FWHM [cm ] FWHM D,s [cm ] FWHM D,a [cm ] FWHM Free [cm ] FWHM ver [cm ] 77.7

3 wavenumbers [cm - ] wavenumbers [cm - ] Fig. S2 Linear absorption spectra of solutions of in, and in the water bend region () and at approximately twice the frequency (). The spectra are corrected for in triglyceride background and normalized on peak intensity between 58 and 68 cm. The vertical lines indicate peak positions. ased on the frequency and frequency shift with increasing fatty acid chain length, the small peak around 324 cm can be assigned to the overtone of the bend vibration ml/l 2.5ml/l wavenumbers [cm - ].8.5ml/l ml wavenumbers [cm - ] Fig. S3 Linear absorption spectra of isotopically diluted water (% :) dissolved in () and () for different water concentrations. The spectra are corrected for in triglyceride background and normalized on peak intensity. The spectral shape does not change significantly with the water concentration, indicating that the contribution of water clusters is negligible wavenumbers [cm - ] wavenumbers [cm - ] Fig. S4 Linear absorption spectra of isotopically diluted water (% :) () and () dissolved in, and at low water concentration (<2.5 ml/l). The spectra are corrected for () and () in triglyceride background and normalized on peak intensity. The spectra are identical within errorbar in the D stretch region () while the water bend vibration still shows a considerable redshift with increasing fatty acid chain length ()

4 275 :9 D 2 :H D 2 pump frequency [cm - ] iso iso pump frequency [cm - ] diff diff probe frequency [cm - ] probe frequency [cm - ] Fig. S5 2DIR spectra of solutions of :9 : () and () in, at.4 picoseconds after excitation. The top row shows the isotropic 2DIR spectrum ( α /3 α 2 α, rotation free) and the bottom row the polarization difference 2DIR spectrum ( α α α, / α, α, cross peaks enhanced). The spectra are normalized on peak intensity. Normalized :9 D 2 :H 2 D cm - pump probe frequency [cm - ] Fig. S6 Crosssections of the isotropic 2DIR spectra at 258 cm pump frequency for :9 : and in, at.4 picoseconds after excitation and normalized at 257 cm probe frequency. The cross peak (at probe frequency 268 cm ) for :9 : is approximately x smaller than for.

5 5 258 cm - excitation cm - excitation cm - excitation Fig. S7 Slices of the 2DIR spectrum at different excitation frequencies, for a solution of :9 : in (solid lines are description with spectral decomposition fit). The colors indicate different ps delay times cm excitation 27.4 ps.5 ps 4 ps 8 ps 2 ps ps probe frequency [cm - ] spectral component detection frequency spectral component [cm - ] lifetime [ps] probe frequency [cm - ] pump frequency [cm - ] Fig. S8 Spectral components () of the 2DIR spectral slices for a solution of :9 : in (Fig.S7), and their corresponding lifetimes () T,2 T,