scholarly journals Collisional relaxation of apocarotenals: identifying the S* state with vibrationally excited molecules in the ground electronic state S0*

2015 ◽  
Vol 17 (16) ◽  
pp. 10478-10488 ◽  
Author(s):  
Florian Ehlers ◽  
Mirko Scholz ◽  
Jens Schimpfhauser ◽  
Jürgen Bienert ◽  
Kawon Oum ◽  
...  
Keyword(s):  
Electronic State ◽  
Ground Electronic State ◽  
Collisional Relaxation ◽  
Vibrationally Excited ◽  
Vibrationally Hot Molecules ◽  
Excited Molecules

The S* signal of carotenoids corresponds to vibrationally hot molecules in the ground electronic state S0*.

AN IMPROVED TECHNIQUE FOR THE OBSERVATION OF INFRARED CHEMILUMINESCENCE: RESOLVED INFRARED EMISSION OF OH ARISING FROM THE SYSTEM H + O2

1960 ◽  
Vol 38 (10) ◽  
pp. 1742-1755 ◽  
Author(s):  
P. E. Charters ◽  
J. C. Polanyi
Keyword(s):  
Infrared Spectrum ◽  
Electronic State ◽  
Vibrational Temperature ◽  
Infrared Emission ◽  
Multiple Reflection ◽  
Ground Electronic State ◽  
Oh Radicals ◽  
Vibrationally Excited ◽  
Improved Technique ◽  
First Time

A multiple reflection apparatus for the observation of infrared chemiluminescence is described. By means of this apparatus infrared emission from the system H + O2 has been identified as being due to vibrationally excited OH radicals in levels v = 1, 2, and 3 of the ground electronic state. The resolved infrared spectrum of the OH fundamental has been observed for the first time without interference from other emission. The most likely source of excited OH is the reaction H + HO2 → OH† + OH. The vibrational 'temperature' of OH† (vibrationally excited OH in its ground electronic state) in our system is in the region of TV = 2240 °K. These findings are discussed in relation to Krassovsky's suggestion that reaction between H and O2 could account for the Meinel hydroxyl bands in the night sky.

Infra-red chemiluminescence I. Infra-red emission from hydrogen chloride formed in the systems atomic hydrogen plus chlorine, atomic hydrogen plus hydrogen chloride, atomic hydrogen plus deuterium chloride, and atomic deuterium plus hydrogen chloride

1960 ◽  
Vol 258 (1295) ◽  
pp. 529-563 ◽  
Keyword(s):  
Electronic State ◽  
Hydrogen Chloride ◽  
Atomic Hydrogen ◽  
Room Temperature ◽  
Ground Electronic State ◽  
Third Body ◽  
Vibrationally Excited ◽  
Red Emission ◽  
Vibrational Levels ◽  
Infra Red

Infra-red emission arising from several room-temperature gas-phase reactions has previously been described by the authors in preliminary communications (Cashion & Polanyi 1958, 1959 a, b, c ). In the present work, details of this new technique are given. Spectra obtained from the systems H + Cl 2 , H + HCl, H + DCl and D + HCl are described. These consist of the resolved spectra of the HCl fundamental transitions (∆ v = 1) in the ground electronic state, the partially resolved first overtones (∆ v = 2) and, in one system, the unresolved second overtones (∆ v = 3). The system H + Cl 2 gives rise to emission from all vibrational levels up to and including v = 6; the system H + HCl from all levels up to and including v = 7. A detailed examination of the spectra obtained from the systems H + HCl, H + DCl and D + HCl leads to the conclusion that these emissions arise from the formation of vibrationally excited HCl or DCl as the product of an association reaction between hydrogen atoms and chlorine atoms (in the presence of some ‘third body’, M ). This result constitutes the first direct evidence for the view that association reactions lead to the formation of highly vibrating molecules (Polanyi 1959). Also consistent with this view is the observation made here that HCl or DCl acting as a third body in association reactions is not excited to levels higher than v = 1. The bulk of the emission observed from the system H + Cl 2 is believed to arise from the exchange reaction H + Cl 2 = HClꜛ v ≼ 6 + Cl (where HClꜛ is vibrationally excited HCl in its ground electronic state). The vibrational distribution of HClꜛ in the system H + Cl 2 , under our experimental conditions, conforms approximately to a Boltzmann distribution for a vibrational temperature of 2700°K. From this observed distribution a calculation of the initial distribution is made, which would indicate that the HClꜛ are formed initially in all accessible vibrational levels, lower levels being favoured over higher. However, this result is based on the arbitrary assumption that vibrational-vibrational exchange between HClꜛ molecules is negligible. The distribution of HClꜛ among rotational levels of v = 1 in the system H + Cl 2 is definitely non-Boltzmann. The excess rotational energy over room temperature equilibrium energy, is shown to come from an even greater excess present in the HClꜛ as originally formed. The absolute intensity of the emission is calculated at ca . 0.005 W. It is estimated that roughly 1 to 10 % of the heat of reaction goes into vibrational excitation.

The flash photolysis of ozone

1957 ◽  
Vol 242 (1230) ◽  
pp. 265-276 ◽  
Keyword(s):  
Electronic State ◽  
Vibrational Energy ◽  
Inert Gases ◽  
Inert Gas ◽  
Ground Electronic State ◽  
Explosive Decomposition ◽  
Kcal Mole ◽  
Vibrationally Excited ◽  
Energy Chain ◽  
Excited Oxygen

The photolytic decomposition of ozone in ultra-violet radiation has been studied by kinetic spectroscopy. It has been shown that vibrationally excited oxygen in its ground electronic state plays a most important part in the decomposition. These molecules have sufficient vibrational energy to bring about dissociation of ozone, thus regenerating oxygen atoms which can again produce vibrationally excited oxygen. The importance of this energy chain is emphasized by comparative studies on the explosive decomposition of pure ozone, and the isothermal decomposition when an excess of inert gas is present. In the former case the O* 2 is removed so rapidly, mainly by reaction with ozone, that no absorption due to it can be detected. Using an excess of inert gas to obtain isothermal conditions it has been possible to observe Schumann–Runge absorption of oxygen molecules in their ground electronic state, with up to 16 quanta of vibrational energy. The vibrational energy distribution of the oxygen molecules formed has an apparent maximum at v " = 13 (53.5 kcal/mole) and falls off sharply at v " = 12 and 16 (49.0 and 63.2 kcal/mole). It is shown that the only reasonable reaction for the production of excited oxygen is O + O 3 → O* 2 + O 2 . Studies on the rate of ozone decay with time have also been carried out and the results analyzed in terms of the rate constants of reactions involving the deactivation of excited oxygen and the three-body recombination O + O 2 + M → O 3 + M . It is shown that the spherically symmetrical and chemically inert gases such as A, He and SF 6 are much less efficient in bringing about recombination than N 2 , N 2 O or CO 2 .

scholarly journals The Populations of H2 Vibrational States in Intense UV Fields Near O-B Stars

1987 ◽  
Vol 115 ◽  
pp. 179-180
Author(s):  
P. E. Dewdney ◽  
R. S. Roger ◽  
N. Robert
Keyword(s):  
Electronic State ◽  
Excited States ◽  
Ground State ◽  
Molecular Hydrogen ◽  
Ground Electronic State ◽  
Vibrational States ◽  
Vibrationally Excited ◽  
B Stars ◽  
Intense Fields ◽  
The Mean

In most places where molecular hydrogen exists in the interstellar medium, it will be found in the ground vibrational and ground electronic state. This will not be so, however, near 0 or early B stars where, in the region just beyond the ionization boundary, populations will be determined by UV fields up to 105 times more intense than the mean interstellar value (4 × 10−16 ergs cm−3 s−1 = 1 Habing unit). The H2 absorbs Lyman-Werner band photons longwards of λ91 nm and subsequent decays to the ground electronic state may lead to dissociation (vibrational continuum) or to one of 14 vibrationally excited states. Molecules in these states have lifetimes of order 1010 s and, in the intense fields, will be exposed to further Lyman-Werner excitation. The probability of dissociation is therefore greatly enhanced by this ‘multiple excitation’, since the number of lines available to vibrationally excited H2 is many times that available to ground-state H2 (Shull, 1978).

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