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The triboluminescence of a variety of mono-and disaccharides including sucrose is luminescence from mo-. lecular nitrogen. The absence of triboluminescence from some saccharides is not a function of crystal size. The diminished intensity of triboluminescence excited in crystals under denitrogenated liquids in which they are insoluble is discussed.The earliest record of triboluminescences (TL), the luminescence caused by the application of mechanical stress to crystals, is contained in the writings of Bacon2 who observed that lumps of sugar emitted light when scraped. The triboluminescence of sugar was known to many other early writers including Boyle who observed that "hard sugar being nimbly scraped with a knife would afford a sparkling light".2 He also observed that the luminescence still occurred when the sugar was scraped under vacuum.In spite of the long history of the T L of sugar, the origin of the luminescence has never been determined. For organic crystals and some inorganic salts, the most common origins are crystal fluorescence3 or phosphore~cence.~-~ The previously postulated* gas discharge origin is rarer. In some cases, room temperature TL can occur from crystals which are not photoluminescent a t that temperature.j We have spectroscopically investigated the T L of mono-and oligosaccharides. We report here spectroscopic proof that the T L of saccharides originates from gas discharge and note general observations regarding the phenomenon.Samples of D-glucose; lactose, maltose, L-rhamnose, and sucrose are triboluminescent while samples of cellobiose, fructose, fucose, galactose, and mannose are not. The T L spectrum of sucrose, a typical member of the triboluminescent sugars, is shown in Figure 1. All T L was excited by grinding the sample in a Pyrex vial with a stainless steel rod. The T L could also be excited by grinding the sample between any hard objects including glass, wood, plastic, and other metals. The spectra were obtained using the method previously reported.6The spectrum shown in Figure 1 is that of the second positive group of molecular n i t r~g e n .~ As we have previously remarked,s an excitation energy of over 11 eV is necessary to excite Nz from the ground state to the emitting 37ru state. The vibrational progression shown arises from the vibrational levels of the 37rg state of Nz.In order to gain insight into the location of the emitting molecular nitrogen, we have measured the relative intensities of the TL of sucrose crystals in a variety of argon stripped solvents in which the sugar is insoluble. In all cases, the intensity of the TL excited under the liquid decreased compared to that excited in air. Typical decreases ranged from a minimum of 38% in benzene through 68% in chloroform to 100% in nujol. No correlation between the intensity and any bulk property of the liquid was found. The absence of a correlation may occur because the intensity is a sensitive function of the mechanical energy applied to the crystal. The lubrication properties of the solvent and/or the softening of...

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Abstract. C3sH42B9PzRh, monoclinic, P21/n, a= 12.669 (6), b=18-587 (4), c=16.041 (7) A, /?=97.08 (4) °, Z=4, Dm=l'29 (2) (flotation), Dx=1.294 g cm -a. The Rh(IIl) ion is complexed by one terminal hydride, one zc-B9CzHx2i " and two triphenylphosphine ligands.