GRUMMAN DATA SYSTEMS CORPORATION
1
Report for Analytical Chemists The gain coefficient G is given by (S) G = η*σ β (λ.) — n 0 a s (X) — Π τ στΜ — r (2) where n 0 , η"', and η,τ are the (num- ber) densities of singlet ground- state, singlet excited-state, and triplet-state molecules, respec- tively; σ#(λ) and σ Γ (λ) are the (molecular) singlet-singlet and triplet-triplet absorption cross sec- tions; and r is the average extrinsic loss per unit length of dye, in- corporating all intracavity losses except the dye absorbances. The average intracavity loss owing to mirror reflectivities iui and R2, for example, is given by r = —ln(i?! X i? 2 )/2 I, where I is the length of the dye cell. The stimulated emission cross section σ 5 (λ) can be shown (S, 4) to be σ,(λ) = A 4 F(X)/&rW (3) where T S is the spontaneous singlet decay time, λ and c are the wave- length and velocity of light in vacuum, η is the index of refraction of the solution, and F (λ) is the fluorescence line shape normalized so f F (λ) d\ equals the quantum yield φ. The total dye concentra- tion η is equal to the sum of no, η*, and n T . Equation 2 can thus be re- written as G — n* (<j g + a s ) — Π τ (σ τ — o- s ) — Πσβ — Τ (4) Since the cross sections can be mea- sured directly or calculated from measurable quantities, G is a func- tion of four independent variables: λ (through the wavelength-de- pendent cross sections), n*, n T , and r and n* and n T can vary both spatially and temporally following the excitation intensity (5). If the intracavity laser intensity I is high, n* can also depend on I through stimulated emission and absorption terms, and Equations 1 and 4 must be solved simultaneously. Great simplification is effected, and the essential physics is dis- played if n* is assumed spatially uniform. This approximation cor- responds experimentally to a cylin- Jtoui does your volumetric dispensing equipment stock up against ours? Whether you're using a semi-automatic pipette or dispensing liquids manually — compare your method to ours. THE GRUMMAN ADP-30DT AUTOMATIC DIGITAL PIPETTE • d i s - penses liquids with better than .5% accuracy · with a repeatability of 0.1% or better · can mix four different fluids simul- taneously · has a calibrated delivery capacity from 0.02 ml. to 21 ml. · accepts a wide range of cans, bottles, ampoules or vials including the new FLEAKER (Reg. Corning™) · has a built-in synchronized conveyor tray • has "no vial/no fill" sensing · can select the number of vials to be filled · stops automatically after filling the last vial · surfaces exposed to fluids are made of selected teflon (Reg. DuPont™) to assure continuous smooth control · has a least count down to 0.02 μ\. through titrating. If you're still not convinced the Grumman ADP-30 has more unique cost and time saving advantages than your present method, ask for a demonstration. Call (516) 575-3282 or 3888 collect. % = β > <« CIRCLE 85 O N READER SERVICE CARD ANALYTICAL CHEMISTRY, VOL. 44, NO. 6, MAY 1972 · 37 A GRUMMAN DATA SYSTEMS CORPORATION BETHPAGE, NEW YORK 11714 [INSTRUMENT SYSTEMS PRODUCTS]
Transcript of GRUMMAN DATA SYSTEMS CORPORATION
Report for Analytical Chemists
The gain coefficient G is given by (S)
G = η*σβ(λ.) — n0as(X) — ΠτστΜ — r (2)
where n0, η"', and η,τ are the (number) densities of singlet ground-state, singlet excited-state, and t r iplet-s ta te molecules, respect ively; σ#(λ) and σΓ (λ) are the (molecular) singlet-singlet and tr iplet- tr iplet absorption cross sect ions; and r is the average extrinsic loss per uni t length of dye, incorporating all in t racavi ty losses except the dye absorbances. The average int racavi ty loss owing to mirror reflectivities iui and R2, for example, is given by r = —ln(i?! X i ? 2 ) / 2 I, where I is the length of the dye cell. The stimulated emission cross section σ5(λ) can be shown (S, 4) to be
σ,(λ) = A 4 F ( X ) / & r W (3)
where TS is the spontaneous singlet decay time, λ and c are the wavelength and velocity of light in vacuum, η is the index of refraction of the solution, and F (λ) is the fluorescence line shape normalized
so f F (λ) d\ equals the quantum
yield φ. The total dye concentration η is equal to the sum of no, η*, and nT. Equation 2 can thus be rewritten as
G — n* (<jg + as) — Πτ(στ — o-s) — Πσβ — Τ (4)
Since the cross sections can be measured directly or calculated from measurable quantit ies, G is a function of four independent variables: λ (through the wavelength-dependent cross sections), n*, nT, and r and n* and nT can vary both spatially and temporally following the excitation intensity (5) . If the int racavi ty laser intensity I is high, n* can also depend on I through st imulated emission and absorption terms, and Equat ions 1 and 4 must be solved simultaneously.
Great simplification is effected, and the essential physics is displayed if n* is assumed spatially uniform. This approximation corresponds experimentally to a cylin-
Jtoui does your volumetric dispensing equipment stock up against ours? Whether you're using a semi-automatic pipette or dispensing liquids manually — compare your method to ours. THE GRUMMAN ADP-30DT AUTOMATIC DIGITAL PIPETTE • d i s penses liquids with better than .5% accuracy · with a repeatability of 0.1% or better · can mix four different fluids simul
taneously · has a calibrated delivery capacity from 0.02 ml. to 21 ml. ·
accepts a wide range of cans, bottles, ampoules or vials including the new
FLEAKER (Reg. Corning™) · has a built-in synchronized conveyor tray • has "no vial/no fill"
sensing · can select the number of vials to be filled · stops automatically after filling the last vial · surfaces exposed to fluids are made of selected teflon (Reg. DuPont™) to assure continuous smooth control · has a least count down to 0.02 μ\. through titrating.
If you're still not convinced the Grumman ADP-30 has more unique cost and time saving advantages than your present method, ask for a demonstration. Call (516) 575-3282 or 3888 collect.
% = β> <«
CIRCLE 85 O N READER SERVICE CARD
ANALYTICAL CHEMISTRY, VOL. 44, NO. 6, MAY 1972 · 37 A
G R U M M A N
DATA SYSTEMS CORPORATION BETHPAGE, NEW YORK 11714
[INSTRUMENT SYSTEMS PRODUCTS]
