Gold Thin Films: Thickness Vs. Transmission

One of the main problems in microscopy is the movement of the specimen from beam irradiation during imaging which can lead to low-resolution images which are blurred. Carbon films on metal grids can cause this specimen drift. Using gold thin films instead of carbon can stop the drift as they are chemically inert and biocompatible, less fragile, extremely conductive and non-oxidizing. Gold thin metal films are often seen as the most significant signal amplification components in electrochemical and optical sensor applications. In surface plasmon resonance (SPR) applications, gold thin metal film has electron densities which have the plasmon frequencies in the visible light range.

Issues of Transmission with Gold Thin Films

The optical properties of gold thin films, such as their absorption and scattering coefficients, are called into question when used in microscopy. Gold thin films are largely reflective, especially at high thicknesses. However, metal films often have a non-zero absorption coefficient which is part of the complex refractive index that governs optical absorption.

Custom Gold Coatings from Platypus Technologies

The complex refractive index and absorption of photons can have a significantly negative impact on the efficacy of radiative techniques. The greater the absorption of the gold thin film, the less accurate the measured change will be. For thicker films this is especially true as substantial absorption inhibits the photons passing through the film, decreasing the amount of photons able to escape the medium, which then limits the intensity of the detected beam. This can lead to the results being skewed.

Gold Thin Films from Platypus Technologies

At Platypus, we only used 99.999% pure gold and titanium within our coating procedure. We only coat substrates under high-vacuum which means there is no concern regarding the contamination of previous substrates.

High transmission with gold is only possible with an ultrathin film, like those sold at Platypus. Our coating process allows the user to have the utmost control over deposition rates and surface roughness, maintaining the most control possible over the thickness and the nanometer-scale flatness of our gold thin films which leads to the optimum surface plasmon resonance response.

Because we only use completely pure metals in our coater, we avoid contamination with even traces of additional chemicals or metals that can impact cultured cells.

If you would like to find out more, you can read about how gold-coated substrates are being used to drive new applications in nanotech. Alternatively, you can learn more about our gold thin films or contact us today for more information.