## 4 In-Situ Technique Combinations  
In most research, neutron scattering is only one of the tools in the experimental toolbox required to obtain the knowledge of the material properties that one is investigating. In certain circumstances, it is beneficial if one can combine neutron scattering experiments with complementary on-line auxiliary techniques, as has become a fairly routine approach at synchrotron radiation facilities [136; 137]. The advantages of being able to simultaneously collect complementary data sets at the same time, using the same sample, outweigh any disadvantages due to the increased experimental complications regarding synchronization of the data sets and access of different probe beams, which cannot always use the same window material. Conditions in which one can consider the use of a multimodal approach are when dealing with spatially inhomogeneous materials or when the time resolution in an experiment is too fast to be able to stitch the data sets in a reliable way that does not create uncertainties in the time-correlation between the different experiments. In both cases, one should try to interrogate the same sample volume with the different probes. The use of on-line Differential Scanning Calorimetry (DSC) with X-ray measurements is a good example where the data quality of the DSC signals suffers somewhat but where the synergy of having two simultaneous data sets outweighs the loss of quality [22]. When the strong peaks in a DSC curve can be correlated to the X-ray frame number, one can correlate the real thermodynamic temperature of the sample with the appropriate X-ray structure. Hence, the correlation can be made with an accurate DSC curve obtained with a well calibrated off-line instrument. The design problems for constructing a similar set-up for neutrons are somewhat larger than those for X-rays, since the beam access window needs to be considerably larger. However, this engineering issue can be overcome as was shown in phase separation experiments on partially deuterated alkanes, \(\mathrm{C_{n}H2_{n+2}C_{m}H(D)_{2n+2}}\). A commercial instrument with an operation range from \(-150\)\({}^{\circ}\)C to \(+500\)\({}^{\circ}\)C was successfully modified to enable neutron beam access. A slight drawback is that it was not feasible to use commercially available DSC pans but instead special pans had to be custom designed and machined [138]. The time resolution that could be achieved in this experiment was 2 min/frame. The combination of Raman scattering with different neutron scattering techniques has been reported over the years [139; 140], including for the protein lysozyme, but these experiments were all carried out at cryogenic temperatures, which is of limited use in soft matter research. However, it was only recently that the cold deformation, i.e., ambient temperature, of low-density polyethylene was followed by both SANS and polarized Raman spectroscopy [141], where the experiments were performed using the same tensile stage but not simultaneously. By combining the different data sets, one can investigate the interplay between chain stretching (SANS) and the transition from amorphous to all trans conformers (Raman). Although these experiments were done separately, with the present generation of portable Raman spectrometers, there is no reason why this could not be carried out simultaneously if the required time-resolution would make this beneficial [142]. Dielectric spectroscopy can provide information at the molecular level about a variety of soft matter processes. For instance, chemical changes, segmental relaxation in polymers, and phase transitions are among the physical phenomena where dielectric spectroscopy can render complementary information to X-ray [143] and neutron scattering [144]. Such experiments were carried out in combination with a strain controlled Couette shear cell on a SANS instrument [145].