I need to run an experiment on the effect of temperature on refractive index of a liquid, and in order to make the change most visible and have the lowest percent uncertainty I need the change in refractive index to be as high as possible. What are some liquid with high changes in refractive index with change in temp, higher change then water ideally.
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the classic choice is kerosene.
answered Oct 8, 2023 at 16:28
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$\begingroup$ Ideally something that isn't plane fuel and therefore highly combustible. $\endgroup$– PP EpicCommented Oct 8, 2023 at 16:34
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$\begingroup$ yes that's right, but kerosene is still combustible, and is commonly used as plane fuel, it is also an irritant to the skin and its fumes are toxic. It's not gasoline you're right, but it still has many downsides to it that make it impractical to run such experiments on due to the extra safety measures needed to be taken. $\endgroup$– PP EpicCommented Oct 9, 2023 at 17:13
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Not a comment about a liquid, but more about the setting.
You may want to do your experiment in a cavity, e.g. by watching transmission reflection from half-mirrored glass slides with liquid in-between. You will pick up smaller changes by bouncing light several times through the liquid.
You may want to use coherent light in a cavity and get it to diffract, e.g. get a Newton's rings type pattern, and record that pattern change as a function of temperature.
You may want to use Brewster's angle to get refractive-index-dependent difference in the reflection for light of different polarizations. You could then use interference between the reflected light to greatly increase your sensitivity to small refractive index changes. Coherent light could help here too
You may want to set up an electrical heater that will periodically heat your liquid and let it cool down. By running experiment over long time you can use something akin to lock-in detection to detect very small changes
