Optical constants of liquid isooctane at 3.39 microm

Area of Science:

• Physical Chemistry
• Optical Properties of Materials

Background:

• Accurate knowledge of the complex refractive index is crucial for various optical applications.
• Temperature-dependent optical properties of organic liquids require detailed investigation.

Purpose of the Study:

• To experimentally determine the complex refractive index of liquid isooctane at 3.39 micrometers.
• To investigate the influence of temperature on the refractive index and extinction coefficient.

Main Methods:

• Employed a two-angle reflectance technique for precise measurements.
• Utilized a fused quartz prism to manage liquid evaporation and prevent index gradients.
• Studied the liquid isooctane over a temperature range of 23 to 80 degrees C.

Main Results:

• The real part of the refractive index showed minimal change, decreasing from 1.440 to 1.406.
• The extinction coefficient significantly increased from 0.0654 to 0.0808 with rising temperature.
• Attributed the increase in extinction coefficient to temperature-induced redistribution of molecular states.

Conclusions:

• The complex refractive index of isooctane is temperature-dependent, primarily affecting the imaginary part.
• Experimental data provides valuable insights into the optical behavior of isooctane across a relevant temperature spectrum.
• Estimated errors are 0.05% for the real part and 3.0% for the imaginary part of the refractive index.