Plasma agriculture based on quantitative monitoring of reactions between fungal cells and atmospheric-pressure plasmas

2012 ◽  
Vol 1469 ◽  
Author(s):  
Masafumi Ito ◽  
Takayuki Ohta ◽  
Keigo Takeda
Keyword(s):  
Uv Radiation ◽  
Absorption Spectroscopy ◽  
Ground State ◽  
Atmospheric Pressure ◽  
Atomic Oxygen ◽  
Fungal Spores ◽  
Ultra Violet ◽  
High Density ◽  
Inactivation Rate ◽  
The Absolute

ABSTRACTA high-density non-equilibrium atmospheric pressure plasma (NEAPP) applied for inactivating fungal spores of P. digitatum is introduced as an environmentally safe and rapid-inactivation method. The contributions of ozone, ultra violet (UV) radiation and ground-state atomic oxygen in the NEAPP on the inactivation of the spores are evaluated using colony count method.The absolute densities of ozone were measured by using ultraviolet absorption spectroscopy. The ozone density increased from 2 to 8 ppm with an increase in the distance from the plasma source, while the inactivation rate decreased. The inactivation rate of plasma was evaluated to be thousand times higher than that of an ozone generator using the integrated number density of ozone. In addition, it was clarified that the contribution of UV radiation to inactivation was not dominant for P. digitatum inactivation by NEAPP by filtering the active species using quartz plate. From these results, we can speculate that the inactivation efficiency of reactive oxygen species (ROS) will be larger than those of others.In order to investigate the effect of ground-state atomic oxygen as one of ROS, the inactivation of P. digitatum spores using an oxygen radical source that employs a high-density atmospheric-pressure O2/Ar plasma. The absolute O density was measured to be 1.4×1014 and 1.5×1015 cm–3 using vacuum ultra violet absorption spectroscopy (VUVAS) using a microdischarge hollow cathode lamp. The behaviors of the O densities as a function of O2/(Ar+O2) mixture flow rate ratio correspond to that of the inactivation rate. This result indicates that ground-state atomic oxygen is concluded to be the dominant species that causes inactivation.

Inactivation ofPenicillium digitatumSpores by a High-Density Ground-State Atomic Oxygen-Radical Source Employing an Atmospheric-Pressure Plasma

2011 ◽  
Vol 4 (11) ◽  
pp. 116201 ◽  
Author(s):  
Sachiko Iseki ◽  
Hiroshi Hashizume ◽  
Fengdong Jia ◽  
Keigo Takeda ◽  
Kenji Ishikawa ◽  
...  
Keyword(s):  
Ground State ◽  
Atmospheric Pressure ◽  
Atomic Oxygen ◽  
Atmospheric Pressure Plasma ◽  
Oxygen Radical ◽  
High Density ◽  
Pressure Plasma

Modeling of the Distinctive Ground-State Atomic Oxygen Density Profile in Plasma Needle Discharge at Atmospheric Pressure

2015 ◽  
Vol 32 (7) ◽  
pp. 075202 ◽  
Author(s):  
Mu-Yang Qian ◽  
Cong-Ying Yang ◽  
Xiao-Chang Chen ◽  
Geng-Song Ni ◽  
Song Liu ◽  
...  
Keyword(s):  
Density Profile ◽  
Ground State ◽  
Atmospheric Pressure ◽  
Atomic Oxygen ◽  
Plasma Needle

Lamb shift of the 1 2 S ground state of deuterium

1956 ◽  
Vol 234 (1199) ◽  
pp. 516-528 ◽  
Keyword(s):  
Relative Intensity ◽  
Ground State ◽  
Quantum Electrodynamics ◽  
Lamb Shift ◽  
Ultra Violet ◽  
Dirac Theory ◽  
Combination Principle ◽  
The Absolute ◽  
Fifth Order

According to modern quantum electrodynamics, the 1 S level (ground state) of hydrogen and deuterium is predicted to lie 0⋅272 6 cm –1 above the energy given by the Dirac theory. In order to obtain an experimental value for this Lamb shift, the absolute wavelength of the L α line of deuterium has been determined by means of a 3 m vacuum grating spectrograph in fifth order. Lines of the series 6 1 S 0 – n 1 P 1 and 6 1 S 0 – n 3 P 1 of 198 Hg observed in the same order were used as standards. The wavelengths of these standards were obtained to ± 0⋅0002Å by the combination principle from lines in the visible and near ultra-violet regions, some of which were newly measured. Both the far ultra-violet Hg lines and L α of deuterium were simultaneously recorded on the plate in absorption. In this way, from six independent plates the wavelength of the L α line of deuterium was found to be 1215⋅3378 ± 0⋅0003 Å. This value refers to an unresolved doublet. If the relative intensity of the two doublet components (2:1) and the temperature of the absorbing column (80°K ) is taken into account and the result compared with the Dirac value of L α , a shift of the 1 2 S level of 0⋅26 2 ±0⋅03 8 cm –1 is obtained. The agreement with the predicted value is very satisfactory.

scholarly journals Resolving photoisomerization dynamics via ultrafast UV-visible transient absorption spectroscopy

2021 ◽  
Author(s):  
◽  
Shyamal Prasad
Keyword(s):  
Absorption Spectroscopy ◽  
Ground State ◽  
Transient Absorption ◽  
Bond Cleavage ◽  
Ultra Violet ◽  
Solvent Polarity ◽  
Transient Absorption Spectroscopy ◽  
Bond Breakage ◽  
Solvent Dependence ◽  
Azobenzene Moiety

<p>Transient absorption spectroscopy has been employed to investigate three photo–active compounds; azobenzene, foldamer controlled by azobenzene, and oxazine. These compounds all have absorption in the ultra–violet regions responsible for their photo–active behavior. Due to this, the current transient absorption setup has been modified to extend the probing wavelength range to 320–650 nm, with the possibility of exciting the photo–active molecule in the ultra–violet.  Azobenzene is valuable in benchmarking and optimizing the transient absorption setup, it shows that the detection window has been extended out to 320 nm. By resolving the ground state bleach we have added support for the assignment of the final decay to thermalization in the ground state. Comparison of relaxation lifetime in acetonitrile and tetrahydrofuran shows no noticeable change in the photophysics of isomerization between the two solvents.  The foldamer family excited state relaxation is similar to azobenzene. There is an extension in the S₁ branching lifetime from 1.1 ps in azobenzene to 1.7 ps for foldamer 1 and 4.2 ps for foldamer 2. The separation of branching on the S₁ surface and relaxation through the S₁ to electronic ground state intersection was possible by comparison of azobenzene and foldamer family. The solvent effects show little difference for all members of the foldamer family expect for foldamer 2, suggesting that the dynamics of the azobenzene moiety are not affected by the larger macro–structure of the foldamer.  For oxazine it has been established, by varying solvent polarity, that isomerization happens through three states; bond breakage, transfer to a dark state, and the final photo–isomer. This is confirmed by further studies completed after the introduction of electron withdrawing fluorine atoms. Carbon–oxygen bond cleavage occurs on the picosecond timescale, with solvent dependent rotation occurring in hundreds of picoseconds. Fluorinated oxazine shows a strong solvent dependence with rotation suppressed for all but the most polar of solvents.</p>

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