# Dorky Poll: Favorite Wavelength

I have two labs today, and a lunch meeting, so no time for detailed blogging about science. It’s been a while since I did a Dorky Poll, though, so here’s one to keep people entertained while I’m working:

“What’s dorky about that?” you ask. You need to give your answer in wavelength units. For extra bonus dorky points, specify an atomic transition of approximately that wavelength.

Personally, I’m kind of partial to the blue-green lines in helium, right around 501 nm. That’s a nice color. The violet line in the hydrogen spectrum, around 435 nm, is also pretty good.

1. #1 Thomas
April 30, 2009

What if your favorite colour isn’t given by any single wavelength?

2. #2 WMGoBuffs
April 30, 2009

This is a question asked by a known goofball theorist in my department at everybody’s thesis defense.

3. #3 PhilipJ
April 30, 2009

I’m building a non-collinear optical parametric amplifier in the blue which is turning out to be slightly trickier than initially thought. Given how much I think about it these days, I’m going to have to say the colour most on my mind is 480nm.

A close second, the fluorescence produced by business cards (most have pigments in them that are excellent for visualizing UV beams) using 257nm light is really stunning.

4. #4 H
April 30, 2009

There are several easy wavelengths that come to mind that are common in the laser-using fields:
He-Ne Red: 632.8nm
Doubled-Nd:YAG green: 532nm
Tripled-Nd:YAG UV: 355nm

5. #5 Eric Lund
April 30, 2009

This one’s easy for me: 557.7 nm. That’s the wavelength of the green in the aurora borealis, and it’s due to the “forbidden” 1S->1D transition in atomic oxygen.

Runners up: 630.0 nm (one of the doublet for the 1D->3P transition in atomic oxygen) and 427.8 nm (which is due to a transition in N2). Both also occur in the aurora borealis.

I knew the wavelengths offhand. I had to look up the precise transitions involved.

6. #6 Craig
April 30, 2009

When I first started in nitride seminconductors, our products were 470 nm, 505 nm, and 525 nm; the first of the three was always the easiest and most reliable, but the last was always the prettiest if you got it working right. (The middle wavelength is the offical spec for green traffic lights, if you’re interested.)

Now I’ve moved on to AlGaN emitters though, so the Deep UV of 270 nm is my favorite at the moment.

(Atomic transitions? I think in bandgaps. Let the guys doing PL figure out what lasers they need to excite my samples.)

April 30, 2009

What if your favorite colour isn’t given by any single wavelength?

Then you’re not dorky enough for this poll.

8. #8 rob
April 30, 2009

i always thought a 568 nm laser would be cool.

9. #9 Steven O
April 30, 2009

Well, no atomic transitions for mine, but they are 410nm and 532nm as those are the wavelengths of the two diode lasers I am using in my research.

10. #10 Sean Carroll
April 30, 2009

1.05 mm. It’s the color of the Big Bang. (Although it helps to have microwave eyes.)

11. #11 Matt Springer
April 30, 2009

Another commenter beat me to it.
Doubled-Nd:YAG green: 532nm

12. #12 MiddleO'Nowhere
April 30, 2009

514.5 nm
We had a 20-watt argon-ion laser in undergrad. Very pretty, but very dangerous. I briefly snagged my arm in the beam when at full power (we were pumping a Ti-Saph laser), not a fun experience.

13. #13 Tercel
April 30, 2009

I like the color of an Ar-ion laser, which I think is 514. Its a very pretty blue-green.

I also like the Rb-87 D2 line, where it is easy to look at hyperfine structure using a cheap diode laser. It isn’t strictly in the human visible range, but even with an etalon narrowed spectrum, you can see a bit of deep red if your eyes are good.

April 30, 2009

21 cm, baby!

Atomic hydrogen spin-flip transition.

(Sean Carroll actually beat me to the peak of the CMB one)

15. #15 Matt
April 30, 2009

Balmer! (The hydrogen line, not the microsoft ape-man).

16. #16 Uncle Al
April 30, 2009

Melting point capillary, teensy bit of iodine, flame seal. Hit with a green laser pointer. You atomic guys miss all the fun of vibronic transitions.

http://home.sou.edu/%7Echapman/ch445/i2uvvis.gif

17. #17 Bee
April 30, 2009

I’m afraid my favorite color is black. That would be the absence of any wavelengths?

18. #18 csrster
April 30, 2009

Favourite colour? M2Ia, the spectral type of the Garnet Star.

19. #19 Ben M
April 30, 2009

0.385625 angstroms. That’s the 32 keV gamma ray from the decay of Krypton-83m.

20. #20 Kevin Reid
April 30, 2009

560 ± 190 nm.

(Whaddaya mean that isn’t a single wavelength?)

21. #21 Anonymous Coward
April 30, 2009

P.S. 23499 cm^-1.

22. #22 Zak
April 30, 2009

5 um to 10 um. It’s a small band in the mid-IR that’s just Chock-Full of roto-vibrational transitions. You can identify pretty much any molecule with an IR absorption or Raman scattering spectrum over this range.
I know it’s over 15x longer than the entire visible spectrum, but it’s small in the scale of the IR spectrum.

If I have to pick a single color I will go with 1500 nm. This is the peak of the black body spectrum at ~2000 K — the maximum temperature of most organic combustion (wood burning fires). This is the color of HOT.

23. #23 Ben
April 30, 2009

1064 nm. Optical trapping beam!

April 30, 2009

1) 214.5 nm (deep UV, sorry), S to P3/2 transition in cadmium ion (singly ionized)

2) 396.8 nm, S to P1/2 transition in calcium ion (singly ionized)

25. #25 featheredfrog
April 30, 2009

As an Amateur Radio Operator, my current favorite “color” is at 40 Meters wavelength. I’m also fond of 2M and 700 cm as well.

Hey, my antennas “see” them perfectly well!

26. #26 David Harmon
April 30, 2009

511 MeV. ;-)

27. #27 Szamba
April 30, 2009

My favorite colour is beyond any scale ;)

28. #28 Cherish
April 30, 2009

10^18 Hz. It’s the color I see whenever I end up in the hospital after crashing my bike.

29. #29 Cherish
April 30, 2009

@25:

Did you hear about the antennas that got married? The wedding didn’t go so well, but the reception was great. :-)

30. #30 Mu
April 30, 2009

I just painted my house sodium yellow (589.0 and 589.6 nm), does that count?

31. #31 Josh
April 30, 2009

@26

David, do you mean 511 keV (electron mass)?

32. #32 Squiddhartha
April 30, 2009

I’m partial to around 2 microns, since it’s in that wavelength that the Milky Way is most clearly an edge-on spiral galaxy…

33. #33 magista
April 30, 2009

Well, I’ve always been quite fond of wearing clothes in tones of the D line transmission for sodium.

And although it doesn’t suit me to wear it, the second line of the Balmer series of hydrogen is a lovely colour. You can see this shade in the sky some times just around sunset.

34. #34 Matt Jarpe
April 30, 2009

Mine is 485, the excitation wavelength of FITC.

35. #35 JP
April 30, 2009

193nm – the deep-UV laser used for deep-submicron CMOS photolithography. I believe it’s argon fluoride.

My chip designs are printed with it, so I can’t help but be partial to it.

36. #36 Jamie
May 1, 2009

My favorite color has no wavelength, for it is an absence, not a presence.

37. #37 Jeff
May 1, 2009

3.26 cm!
Without that one, all the other wavelengths are just guesses.

38. #38 Lethe
May 1, 2009

4.5 um, from the 4I9/2 to 4I11/2 transition of erbium. I’ve spent a distrurbing portion of my professional life worried about that transition.

39. #39 Dr. Decay
May 2, 2009

I’m surprised how long it took for someone to mention the Sodium D line(s), 589 nm. I knew a professor who called sodium “the people’s atom”. Hydrogen was for theorists and rich kids who could afford UV lasers and rf discharges. But it’s true that that was in the day’s when Rhodamine 6g was THE laser dye. Still, I think Art Schawlow would have agreed.

May 2, 2009

I knew a professor who called sodium “the people’s atom”. Hydrogen was for theorists and rich kids who could afford UV lasers and rf discharges. But it’s true that that was in the day’s when Rhodamine 6g was THE laser dye. Still, I think Art Schawlow would have agreed.

More recently, I’ve heard rubidium referred to as “God’s atom” (I think attributed to Eric Cornell), because it has such convenient properties for BEC work. 780nm is a pretty good wavelength, too.

41. #41 Kevin
May 22, 2009

Spent some time studying the H Balmer lines emitted by close binary stars. The H-beta n=4-2 transition (4865 A) was my favourite. Not very exotic but solid and dependable.

May 22, 2009

I like Van Morrison’s original version best.

43. #43 Lord
May 22, 2009

435.833 nm, the indigo mercury line

44. #44 Liz
May 22, 2009

I’ve been doing an awful lot of HPLC at 200 and 205 nm these days. The ACN needs to be really clean for that.

45. #45 photon
May 24, 2009

555nm – peak of the human photopic spectral sensitivity function (Vλ)

46. #46 Anne
May 24, 2009

I’m with the (other) ham – down around 1m is where the pulsars get interesting.

47. #47 Anne
May 24, 2009

I’m with the (other) ham – down around 1m is where the pulsars get interesting.

48. #48 tatil
May 25, 2009

Spent some time studying the H Balmer lines emitted by close binary stars. The H-beta n=4-2 transition (4865 A) was my favourite. Not very exotic but solid and dependable.
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