The real-time SPR spectrum of wet steam
is recorded online with continuous spraying (Figure 3e). Unlike the SPR spectra shown in Figure 2b where the prism is immersed in water, distinct changes in both resonant position and reflected light intensity are observed. With large droplets formed, the resonant peak shifts to a longer wavelength and finally reaches the SPR wavelength of water-Au system. The changes in intensity can be understood to be from the size variation of water droplets. Intuitively, the intensity is related to the surface area covered by water droplets. Meanwhile, the shift of the LEE011 clinical trial resonance can be attributed to the interaction of the droplets on top of the surface. Figure 3 Distributions of water droplets and corresponding SPR spectra. (a, b, c, d) Distributions of water droplets on the SPR system with continuously spraying wet steam onto the sensor surface. (e) The corresponding SPR spectra. According to the dispersion relation of SPR, the effective permittivity of air droplet (two phases) composition can be obtained without a doubt. There exist several theories which can calculate the effective permittivity of such mixtures. One of the most widely used formulations is the Maxwell Garnett (MG) theory . Unfortunately, MG theory and other dielectric mixture theories  are www.selleckchem.com/products/mk-4827.html useful only for the case when the gap size between
the droplets is far less than the effective wavelength. Notice here that the ratio of gap size of the adjacent droplets check details to effective wavelength of SP is between 101 and 102; therefore, the steam wetness cannot
be simply derived Non-specific serine/threonine protein kinase from the summation of the two-phase behavior. In our experiment, the SPR spectrum of wet steam is actually a contribution of three parts: air, droplets, and their mutual interaction. By analyzing the curves in Figure 3e, we find that all curves have a Gaussian line shape, which allows us to use a Gaussian model to post-process the experimental results. As measured above, the line shape of the SPR spectrum for air-Au or water-Au system does not change for a fixed incident angle. Thus, the SPR curve of wet steam can be reasonably decomposed into air, water, and interaction parts. Applying a similar technique for all curves in Figure 3e, we can well fit the experimental measurements analytically as shown in Figure 4a. Figure 4b,c shows the fitted curves for air-Au and water-Au contributions, respectively. It should be noted that the reflectivity of the air part decreases while that of the water part increases along the arrow direction. This seems to conflict with the finding of Figure 2b, where increased water ratio leads to reduced reflectivity. However, we would like to emphasize that the spectral response shown in Figure 2b is a whole effect contributed from both water-Au and air-Au portions as discussed previously.