Solarized Glass Fluorescence: Medicine Bottle

From the local rockshop (and antique store) comes this 4" tall antique medicine bottle. The bottle is an early 20th century bottle made by Grace & Rodinson between 1906 and 1932. (see: www.sha.org/bottle/medicinal.htm)

To enhance its transparency a bit of manganese dioxide (aka "glassmaker's soap") was added to the glass. The manganese oxidized the iron impurities and was itself, chemically reduced.

Under prolonged periods of UV radiation from the sun, the manganese was photo-oxidized which imparted a purple or pink hue to the glass. The purple of the bottle is very faint and was hard to photograph.

The oxidized manganese within the silica matrix of the glass fluoresces green under ultraviolet light much like willemite which contains Mn2+ impurities replacing zinc within the zinc silicate matrix. The tetrahedral cage of oxygen atoms in willemite results in an efficient absorption of UV light which allows the manganese ion to fluoresce in a very characteristic green color peaking at 525nm with no sensitizer required.

This is in contrast to minerals such as calcite and halite in which the Mn2+ ion is inside an octohedral cage of oxygen atoms (or chlorine atoms for halite) which makes UV absorption more difficult and so requires a sensitizer such as lead to make the manganese ion fluoresce in the characteristic red-orange color peaking around 620-630nm.

The fluorescence mechanism of the solarized glass appears to be similar to that of willemite. One major difference is that willemite is more active under UVc and less so under UVa which seems to be the opposite case for solarized glass. This may be explained by the fact that soda/lime glass is not very transparent to UVc and the amount of Mn ions in the glass is very small compared to the amount on the surface of willemite.

This experiment was inspired by the work of Bob Fosbury: see www.flickr.com/photos/bob_81667/6226788474/

Contains:
Glass - possibly soda/lime (FL Green >UVab) : Mn2+ or Mn3+ ?

Shown (left > right) under white light, UVa and UVc.

Key:
WL = White light (halogen + LED)
FL = Fluoresces
PHOS = Phosphorescent
UVa = 368nm (LW), UVb = 311nm (MW), UVc = 254nm (SW)
'>' = "stimulated by:", '!' = "bright", '~' = "dim"

Obtained from Highland Rocks and Gems' Rockyard, Burns OR, USA.

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