Photochemistry of Fe(CO)5 adsorbed onto porous Vycor glass

Nature and distribution of tungsten oxides in porous Vycor glass

“…The effect is not as large, but the redistribution of tungsten parallels that found with Fe(CO) 5 ; an increase in the outer volumes of the silica matrix at the expense of that in the interior of the sample [25]. W(CO) 6 is not as volatile as Fe(CO) 5 , but like Fe(CO) 5 , W(CO) 6 physisorbs into PVG and exhibits a high quantum efficiency of CO loss, Φ co = 0.84 ± 0.09 [3,34], similar to that found with physisorbed Fe(CO) 5 , Φ co = 0.96 ± 0.04 [40]. Since release of one CO into the 7 ± 3 nm diameter pores of PVG at room temperature increases the pressure within the pore by close to 0.2 atm [25], the redistribution of tungsten is attributed to CO pressure gradients that develop within the PVG matrix during photolysis.…”

Photodeposition of Diffraction Gratings in Glass: A Comparison of Lithographic, Laser Writing and Holographic Deposition

“…Fe(CO) 5 is highly volatile and physisorbs onto PVG without disruption or signi® cant distortion of the complex's primary coordination sphere. 3 Prior to photolysis, distribution measurements show that the complex uniformly impregnates the outermost volumes of glass to a depth of ; 1600 m m into the glass. 3,6,11 Because of its high volatility and weak interaction with the surface, however, as the photolysis consumes Fe(CO) 5 in one region of PVG, unreacted Fe(CO) 5 diffuses into the exposed region.…”

“…3 Prior to photolysis, distribution measurements show that the complex uniformly impregnates the outermost volumes of glass to a depth of ; 1600 m m into the glass. 3,6,11 Because of its high volatility and weak interaction with the surface, however, as the photolysis consumes Fe(CO) 5 in one region of PVG, unreacted Fe(CO) 5 diffuses into the exposed region. 3,6 The extent of diffusion occurring in a speci® c experiment depends on the loading, excitation intensity, diffusion rate, and writing rate, which is 1 cm/s in these experiments.…”

“…Fe(CO) 5 (Aldrich) was used without further puri® cation since electronic and IR spectra of the vapor- ized compound agreed with published spectra. 3 Polished 2.5 cm 3 2.5 cm 3 1.0 m m samples of Corning' s code 7930 porous Vycor glass were continuously extracted with distilled water for m ore than 24 h, dried at room temperature under vacuum , and calcined at 650 8 C for at least 72 h. 3 The glass samples were stored at this temperature until needed, at which point the sample was removed and cooled to room temperature under vacuum.…”

“…Impregnation was accomplished by a previously described vapor deposition technique. 3 The amount of Fe(CO) 5 adsorbed was determined by com paring the optical density of the impregnated samples to samples containing known amounts of Fe(CO) 5 . 3 The samples prepared in these experiments typically contain 10 5 m ol of Fe(CO) 5 /g of PVG.…”