Questions tagged [optical-properties]
Questions related to color as well as the reflecting and refracting properties of chemicals.
1
vote
1answer
36 views
What is the refractive index of poly(methacrylamide)?
I've been looking for the index of refraction for poly(methacrylamide). I searched several vendors and in https://polymerdatabase.com/ with no success. Is there any database where I can find this ...
3
votes
0answers
22 views
How to align povidone-iodine molecules in order to look for optical polarization?
In this answer I mention how early polarizing filters (e.g. sunglasses) were made by doping a polymer with iodine atoms and then stretching the film to orient the polymer molecules.
Electrons donated ...
5
votes
0answers
88 views
What compound has the strongest optical rotation of polarised light?
A question recently asked here whether compounds know to be chiral can have non-measurable optical rotations: Are there chiral compounds that don't rotate plane-polarized light?.
Apparently they ...
6
votes
1answer
462 views
Are there chiral compounds that don't rotate plane-polarized light?
I know that meso compounds have chiral centers but don't rotate plane-polarized light, and I know that there can be non-traditionally chiral compounds (e.g. ones with large substituents that prohibit ...
5
votes
3answers
163 views
Can two lone pairs in different orbitals make a chiral centre?
Is it possible that if the two lone pairs in a molecule occupy different orbitals, then could this make the molecule chiral? What I mean is, suppose a carbon atom is attached to two different atoms ...
0
votes
2answers
177 views
Why does 1,3-dichloropropane not show stereoisomerism?
It is a multiple choice question:
Which compound does not show stereoisomerism?
A 1,2-dichloroprop-1-ene
B 1,2-dichloropropane
C 1,3-dichloroprop-1-ene
D 1,3-dichloropropane
I ...
2
votes
1answer
512 views
What happens when (+) 2-iodobutane is treated with NaI in acetone?
After treating the compound with NaI, we should follow SN2 mechanism and the product will follow an optical inversion, giving us (-)2-iodobutane, but the answer is (±)2-iodobutane.
After going ...
-1
votes
1answer
289 views
How is Volume an Extensive Property? [closed]
Based on the following definitions, can anyone explain why volume is an extensive property?
Extensive Property: Properties that depend on the amount of matter in a sample.
Volume: the amount of ...
3
votes
2answers
216 views
Why is FEP transparent and PTFE not?
fluorinated ethylene propylene (FEP) is close relative of poly(tetra-fluoroethylene) (PTFE), both only contain fluorine and carbon atoms,both have very similiar properties yet FEP is relatively ...
11
votes
1answer
835 views
How is polarization of light measured?
Chiral molecules are classified as dextrorotatory (+) or levorotatory (-) depending on whether they rotate plane-polarized light (ppl) to the right or left.
My question is, how is such a measurement ...
3
votes
1answer
91 views
Does alumina become transparent at high temperatures?
Consider a normal opaque alumina crucible. I've heard that they become transparent at higher temperatures and therefore, are not appropriate for high precision DSC (caloric) measurements. The reason ...
2
votes
1answer
81 views
How many stereoisomers can exist for 4,5-bis(3-hydroxyoct-1-en-1-yl)cyclopentane-1,3-diol?
Q.10 For the given compound $\ce{X}$, the total number of optically active stereoisomers is ____.
This is from JEE Advanced 2018 second question paper.
I thought the answer to be at least 32 ...
0
votes
2answers
150 views
Meso and achiral does both term means the same?
When a molecule has plane of symmetry, or centre of symmetry it is termed as an achiral compound (though it contain some chiral centres). Same goes for the meso compounds due to the internal ...
0
votes
0answers
40 views
Effect of interaction between lactic acid and glucose monohydrate on optical rotation
Would anyone know why I get double the expected optical rotation (OR) result for a solution containing D(+)-glucose and L(+)-lactic acid in comparison to a solution of D(+)-glucose on its own?
When I ...
-1
votes
0answers
37 views
What is the most optically dense gas [duplicate]
I am interested in the answer because based on my understanding of this topic where density of an object affects the optical density of that object. A gas has variable density on different height in a ...
0
votes
3answers
95 views
When an electron returns to it's ground state does it release the same wavelength of light that promoted it in the first place?
If this is true, I fail to understand why we see colour at all -- wouldn't any wavelengths absorbed by electron promotion be inconsequential to colour because there would an equal amount, and ...
0
votes
1answer
52 views
What does it mean if I am unable to write RS configuration for a compound?
We had to write all possible optically active monochloro derivatives of 2-methylbutane.
I was unable to write RS configurations for 1 and 3, since they have carbon atoms with more than one same groups ...
2
votes
1answer
49 views
Intensity of “surface plasmon resonance “ absorption peaks for a nano-rod
The SPR absorption spectrum of a nano-rod is seen to have two peaks with the longer wavelength peak corresponding to the absorption by the longitudinal plasmons and the other to the transverse ...
1
vote
0answers
38 views
Is it possible to have a fully opaque 'switch glass'?
Current switch glass (smart glass) technology permits for a transparent glass to become semi-transparent, i.e., translucent.
For my application, I was wondering if it was possible to make a 'smart ...
-1
votes
1answer
492 views
Conditions for Chirality in optical isomerism [duplicate]
Is it necessary that any atoms which is chiral must have 4 different atoms around the central chiral atom(maybe it can be carbon if it's organic molecule) bonded to it?
More specifically:
I mean can't ...
6
votes
2answers
912 views
Effect of direct exposure to sunlight on various drugs
Today, we were discussing optical activity in class and our teacher said that some drugs are kept in dark coloured bottles to avoid direct exposure to sunlight. Same is the case with some other drugs ...
0
votes
1answer
306 views
Refractive index of barium sulfate
What is the refractive index of barium respectively where do I find it? I only find values for alpha, beta and x-ray radiation like on https://pubchem.ncbi.nlm.nih.gov/compound/barium_sulfate#section=...
5
votes
1answer
87 views
Optical techniques for kinetics studies
What optical methods can be used to measure the concentration of reacting gases in a reactor during an exothermic and fast reaction? I need to monitor and measure the local concentration of my gases (...
22
votes
1answer
597 views
How to think of solvated electrons?
This excellent answer explains at length what's happening in this fascinating video entitled Liquid Electrons - Periodic Table of Videos. In the screenshot below, the metallic-looking solvated ...
5
votes
1answer
151 views
How do I run MP2 and/or CCSD-level hyperpolarizability calculations with GAMESS?
I have used GAMESS before for TDHF (RPA) / TDDFT level first hyperpolarizability ($\beta$) calculations. However, I cannot figure out how to calculate $\beta$ with MP2 and CCSD for comparative ...
1
vote
1answer
186 views
How do chemical bonds increase molecular refractivity?
I see that the molecular refractivity of a compound consists of the refractivity indexes of its composite atoms and chemical bonds, and that the refractive index $n$ of a substance increases with its ...
0
votes
2answers
95 views
Permanent cloudy colloid with water
I need to make a cloudy white liquid where the particles won't eventually settle out. It will be exhibiting the Tyndall effect for a very long time.
I'd use milk, but I don't want it to become rancid....
6
votes
1answer
263 views
D-Threose: reduction and optical activity
I've bumped into this exercise:
Judging by the mechanism of reaction between D-threose and $\ce{NaBH4}$, do you think the final product will be optically active?
To me looks like a reduction, ...
4
votes
1answer
53 views
Finding a substance which has a continuous gradient in refractive index
I need to find a substance whose refractive index is constantly changing and directly proportional to the square root of the depth. I know I'm looking for a lot, but I'd really appreciate any ideas or ...
5
votes
0answers
38 views
Is there any molecule describable by three-level with mixed parity and transition dipole moments in different directions?
I would like to know if there are molecules described by a three-level system with mixed parity and transition dipole moments in different directions. By mixed parity I mean all three transitions can ...
16
votes
1answer
727 views
What is happening in this video of solvated electrons donated from sodium in ammonia?
I just saw the Periodic Video Liquid Electrons - Periodic Table of Videos where sodium is added to liquid ammonia. The demonstration shows that even if electrons are solvated, if you have a high ...
4
votes
0answers
821 views
Home science optical absorption test for approximate caffeine quantity in coffee?
I started with How can you measure the caffeine content of a liquid at home? in the cooking stackexchange, but the test strips were only qualitative (yes/no) and don't seem to exist anymore, and the ...
8
votes
1answer
211 views
Discovery of optical activity of enantiomers - where did the idea of using polarized light came from?
According to Wikipedia, optical activity was first observed in 1811 in quartz. Louis Pasteur's contribution is also mentioned there and in other sources as a major advancement in establishing optical ...
10
votes
1answer
172 views
Optical activity of starch
I found this beautiful picture of starch granules in this German Wikipedia article about optical activity. Unfortunately, I have no idea what am I looking at. What are these crosses and why are they ...
5
votes
0answers
42 views
Is optical activity of a given compound a statistical picture?
When optical activity is taught it is done in terms of single molecules. But when it is actually measured it is done on a large collection of such molecules. So, how does the asymmetry manifest itself ...
3
votes
1answer
118 views
Suggestions for 200-600 nm range transmitting polymers/materials
I am a student of physics who is doing research related to Cherenkov measurements. For that purpose, I need suggestions for some materials that have the following properties:
$80\%$ transparency in ...
6
votes
2answers
3k views
UV-Transparent Plastic?
I am looking for a type of plastic, preferably in the form of a sheet or film, that is weatherproof, durable, flexible, and both transparent and UV-transparent. Most films I've seen so far are treated ...
3
votes
1answer
107 views
Transparency and partially deuterated polymers
I've been skimming over the literature and have come into some conflicting information about the optical properties of partially deuterated polymers. From what I've seen, in general deuterated ...
3
votes
2answers
403 views
Can a system of 2 consecutive Biphenyl systems be optically active , even if any adjacent biphenyl systems arent optically active?
This question came in an online test, where they asked whether or not 22,26-dibromo-12,32-dichloro-23,25-diiodo-16,36-dimethyl-11,21:24,31-terphenyl was optically active. (The answer is that it is ...
1
vote
0answers
104 views
Calculating Optical Absorption Spectra using Ab Initio Computations
My main question is, How does one compute the optical absorption spectra of a molecule by using say, Configuration Interaction energy and associated transition dipole moments.
I am trying to use an ...
1
vote
2answers
3k views
Can diastereomers form a racemic mixture?
In my book, it says racemic mixture is the mixture of + and - optical isomers and it is optically inactive. This means enantiomers (optical isomers which are mirror images to each other) can form ...
3
votes
0answers
76 views
What are open access sources for approximate magnetic susceptibility of liquid rocket propellants?
This question asks if the comparatively large paramagnetic susceptibility of liquid oxygen (LOX) is considered when designing rocket tank and engine systems. This comment suggests fuels such as RP-1 (...
1
vote
1answer
83 views
optical rotation of styrene oxide
Which optical isomer of Styrene Oxide would be produced if it is synthesized via epoxidation of the halohydrin. i.e.
Is there a way to deduce this? I assume it would depend on which isomer the ...
1
vote
1answer
702 views
Isomers of coordination compounds
Does [Pt(CH3-CH(NH2)(COO-))2] show geometrical and optical isomerism?
According to me Pt should be dsp2 hybridised giving a square planar geometry. So it is of the form M(aa)2 type. The ligand ...
2
votes
2answers
79 views
Why are fats glossy?
I am talking about the standard fats we see in everyday use (triglycerides). It seems that no matter what the composition, saturated or unsaturated, all fats are glossy when liquid. I don't know if ...
1
vote
0answers
29 views
Why are certain substances clear/invisible? Can we create invisible objects? [duplicate]
This is more so a question of how light interacts with matter. For example, why are substances like oxygen generally invisible? If the light hitting the molecules were absorbed, it would appear black, ...
1
vote
1answer
1k views
A substance that is immisiscible with water and that can be made cloudy
I need to identify a substance that is immiscible with water that is or can be made cloudy.
At the moment I'm using glycerol, but I don't know how to make glycerol cloudy nor is it perfectly ...
3
votes
0answers
40 views
What is the reason behind optically activity of compounds [duplicate]
I am currently being taught optical activity of compounds and I had this question:
Optical rotation (optical activity) is the turning of the plane of linearly polarized light about the direction of ...
3
votes
1answer
230 views
What kind of optical activity requires chirality?
From "Meso compound" in Wikipedia:
A meso compound or meso isomer is a non-optically active member of a
set of stereoisomers, at least two of which are optically active. This
means that despite ...
1
vote
1answer
107 views
Refractive properties of materials?
I've just read this article about meta-materials with 0-refractive index, which potentially may "permit" light with super-luminous rate /under rate is meant the propagation of light's phase, which ...
