1,202 reputation
411
bio website daniel.farrell.name
location Tokyo, Japan
age
visits member for 4 years, 7 months
seen 11 hours ago

I know how to use the grey square -- do you?


1d
comment Definition of luminescence
I think that is a good definition within the context of solid state physics. You could also say something like, "emission resulting in radiation with chemical potential", but this is perhaps too narrow a definition! I generally think of luminescence as radiation resulting from electronic recombination where the electronic population is in an excited state (i.e. not in chemical equilibrium).
Aug
25
comment What is the relationship between entropy and work?
Yes, it's called the Carnot Efficiency, en.m.wikipedia.org/wiki/Carnot%27s_theorem_(thermodynamics) but to derive it you have to assume conservation of energy and entropy.
Aug
25
comment What is the relationship between entropy and work?
Yeah that's better phrasing, thanks. Updated.
Aug
20
comment Spherical and chromatic aberration correction
Why not use a microscopy lens? Internally they have multiple lenses which can correct for abbreviation.
Aug
15
comment Way of measuring thickness of a glass
Too should really add your ideas first....
Aug
14
comment Material that changes transparency when lased from side?
Saturable absorption mirrors rp-photonics.com/semiconductor_saturable_absorber_mirrors.html
Aug
1
comment How will open-circuit voltage affect the Fermi Level Difference
This is not specific enough to answer. What materials? What are the Fermi-levels locations? When materials come into contact the Fermi-levels align until a space charge halts any further change.
Aug
1
comment Does light ever experiences acceleration?
Never thought about it like that before, how curious!
Jul
29
comment What causes this IR emission in UV 365nm LED?
How did you remove the possibility of grating harmonics? What does your spectrometer setup look like?
Jul
25
comment Why do particles in a medium have different speeds?
Statistical mechanics can answer this. The maxwell Boltzmann distribution of velocities of an ideal gas describes a system that has come into equilibrium with it's degrees of freedom. Moreover the particles are distributed ergodically in phase space and thus represent the lowest energy/maximum entropy configuration of these particles. My hunch is that a uniform distribution of velocities could indeed have the same total energy but will also have lower entropy and is thus an unstable configuration. As for a more mechanical description I need to think harder! Great question a big +1 from me.
Jul
25
comment Why are mediums always represented as straight and parallel lines in Ray optics?
This diagram is teaching you the very important concept of refraction. Refraction also happens on curved surfaces but the additional complexity will obscure the same underlying mechanism.
Jun
13
comment Asymmetric photoluminescence spectra
Google is your friend. encrypted.google.com/…
May
10
comment How do the Fermi level, HOMO and LUMO change with doping?
If you provide some references that mention constant fermi-level we can probably tease this apart.
May
9
comment How do the Fermi level, HOMO and LUMO change with doping?
Why is the Fermi level constant with doping? This is the level of 50% occupancy; this should change with doping.
May
8
comment Steady State Solution for Carrier Concentration of Intrinsic Silicon in an Electric Field
This is pretty difficult. You also need to solve the Poisson equation to provide $E(x)$. The standard approach is to user the Boltzmann approximation and change variables to from carrier densities to quasi-Fermi-levels. Then you need to discretise the equations (FD, FVM or FEM) and include some form of exponential fitting to keep the equations stable when the Peclet's number is large. Then for accurate solutions some form of adaptive mesh refinement should be used. All in all a very tricky problem! Take a look at the pn-junction solvers on nanohub.org they might get you started.
May
4
comment Diodes in AC current
If you move it very quickly you will still be able to see the on-off cycle at 60Hz as streaks.
May
4
comment Is refraction of light a thermodynamic process?
Total internal reflection has a thermodynamic/statistical interpretation: is a mismatch between the plentiful internal optical modes and the fewer modes available in the less optically dense material across the interface. I have not thought about a similar analogue for refraction but I imagine the same mental model could be used to describe this process.
Apr
29
comment How to convert the molar attenuation coefficient, ie. molar absorptivity, to heat capacity?
Nice answer! But does not include how to convert from spectroscopy measurements to heat capacity which was OP's questions.
Apr
23
comment When they say the universe was the size of a baseball about a billion billion billion billionth of a second
It means the whole universe. This is important cosmological point because inflation solves the horizon problem (the near uniform temperature distribution of the night sky).
Apr
19
comment Optical system for cloning an image of a light source?
This already does what you want (3 criteria in your question). I don't understand what you are talking about!