Photophysical and photosensitized generation of singlet molecular oxygen (1.DELTA.g) in micellar solutions at elevated pressures. Measurement of singlet molecular oxygen solvent to micelle transfer rates via both molecular diffusion and energy transfer

The vibrational energy distribution in molecules which have quenched O 2 ( 1 ∑ + g ) to O 2 ( 1 ∆ g ) or O 2 ( 1 ∆ g ) to O 2 ( 3 ∑ - g ) is interpreted in terms of the statistical theory. This theory is extended to include cases where initial rotational and translational energy contributes to vibrational excitation of the products. A common linear surprisal plot is observed in the quenching both of O 2 ( 1 ∑) and O 2 ( 1 ∆) by a number of molecules. Strongly inverted vibrational distributions with ⋋ v = - 7.5 are inferred for both products of the quenching step.

Download Full-text

Available potential energy and buoyancy variance in horizontal convection

Journal of Fluid Mechanics ◽

10.1017/s0022112009006685 ◽

2009 ◽

Vol 629 ◽

pp. 221-230 ◽

Cited By ~ 33

Author(s):

KRAIG B. WINTERS ◽

WILLIAM R. YOUNG

Keyword(s):

Energy Transfer ◽

Potential Energy ◽

Energy Budget ◽

Molecular Diffusion ◽

Thought Experiment ◽

Mechanical Energy ◽

External Energy ◽

Additional Energy ◽

Transfer Rates ◽

Available Potential Energy

We consider the mechanical energy budget for horizontal Boussinesq convection and show that there are two distinct energy pathways connecting the mechanical energy (i.e. kinetic, available potential and background potential energies) to the internal energy reservoir and the external energy source. To obtain bounds on the magnitudes of the energy transfer rates around each cycle, we first show that the volume-averaged dissipation rate of buoyancy variance χ ≡ κ 〈|∇b|2〉, where b is the buoyancy, is bounded from above by 4.57h−1κ2/3ν−1/3b7/3max. Here h is the depth of the container, κ the molecular diffusion, ν the kinematic viscosity and bmax the maximum buoyancy difference that exists on the surface. The bound on χ is used to estimate the generation rate of available potential energy Ea and the rate at which Ea is irreversibly converted to background potential energy via diapycnal fluxes, both of which are shown to vanish at least as fast as κ1/3 in the limit κ → 0 at fixed Prandtl number Pr = ν/κ. As a thought experiment, consider a hypothetical ocean insulated at all boundaries except at the upper surface, where the buoyancy is prescribed. The bounds on the energy transfer rates in the mechanical energy budget imply that buoyancy forcing alone is insufficient by at least three orders of magnitude to maintain observed oceanic dissipation rates and that additional energy sources such as winds, tides and perhaps bioturbation are necessary to sustain observed levels of turbulent dissipation in the world's oceans.

Download Full-text

Energy transfer in the quenching of singlet molecular oxygen - II. The rates of formation and quenching of vibrationally excited molecules

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1977.0134 ◽

1977 ◽

Vol 356 (1686) ◽

pp. 295-306 ◽

Cited By ~ 11

Keyword(s):

Energy Transfer ◽

Molecular Oxygen ◽

Vibrational Relaxation ◽

Vibrational Excitation ◽

Rate Coefficients ◽

Singlet Molecular Oxygen ◽

Vibrationally Excited ◽

The Absolute ◽

Excited Molecules ◽

Kinetics Of

The absolute efficiencies for the vibrational excitation of molecules which quench singlet molecular oxygen have been determined from measurements of their infrared chemiluminescence and kinetics of relaxation. The systems studied were NO and CO with O 2 ( 1 ∆ g ) and NO, CO, HCl, DCl, H 2 O, D 2 O, CO 2 , N 2 O, NH 3 and C 2 H 2 with O 2 ( 1 ∑ + g ). Rate coefficients for the vibrational relaxation of a number of these molecules by molecular oxygen were also determined.

Download Full-text