AN EXPERIMENTAL STUDY OF BAND INTENSITIES IN THE FIRST POSITIVE SYSTEM OF N2: II. THE TRANSITION MOMENT

1954 ◽  
Vol 32 (7) ◽  
pp. 475-479 ◽  
Author(s):  
R. G. Turner ◽  
R. W. Nicholls
Keyword(s):  
Experimental Study ◽  
Electronic Transition ◽  
Transition Probabilities ◽  
Transition Moment ◽  
Positive System ◽  
Internuclear Separation ◽  
Electronic Transition Moment

Experimental band intensities of the first positive system (B3Πg → A3Σu) of nitrogen are used together with theoretical transition probabilities to determine the dependence of the electronic transition moment on the internuclear separation. Over the range 1.17 < r < 1.59 Å of internuclear separation, this dependence may be represented by Re(r) = const. × exp (−3.02 r).

AN EXPERIMENTAL STUDY OF BAND INTENSITIES IN THE FIRST POSITIVE SYSTEM OF N2: I. VIBRATIONAL TRANSITION PROBABILITIES

1954 ◽  
Vol 32 (7) ◽  
pp. 468-474 ◽  
Author(s):  
R. G. Turner ◽  
R. W. Nicholls
Keyword(s):  
Experimental Study ◽  
Electronic Transition ◽  
Transition Probabilities ◽  
Transition Moment ◽  
Positive System ◽  
Vibrational Transition ◽  
Internuclear Separation ◽  
Electronic Transition Moment ◽  
Infrared Spectrometer ◽  
Integrated Intensities

Integrated intensities of 52 bands of the N2 first positive system have been measured using a recording infrared spectrometer. These data have been interpreted as vibrational transition probabilities which were compared with theoretical values calculated under the assumption that the electronic transition moment is independent of internuclear separation. The comparison shows that the assumption is not valid for this electronic transition.

AN EXPERIMENTAL STUDY OF THE BAND INTENSITIES IN THE CN RED SYSTEM

1958 ◽  
Vol 36 (1) ◽  
pp. 127-133 ◽  
Author(s):  
R. N. Dixon ◽  
R. W. Nicholls
Keyword(s):  
Experimental Study ◽  
Carbon Tetrachloride ◽  
Electronic Transition ◽  
Transition Moment ◽  
Active Nitrogen ◽  
Electronic Transition Moment ◽  
System A ◽  
Condon Factors ◽  
Franck Condon

Experimental band intensities in the CN red system, A (2Πi) →X(2Σ+), have been measured using an active nitrogen – carbon tetrachloride source. Using calculated Franck–Condon factors qν′ν″ the electronic transition moment Re(r) is found to vary little over the range 1.04 < r < 1.27 Å.

A METHOD OF DETERMINING THE ELECTRONIC TRANSITION MOMENT FOR DIATOMIC MOLECULES

1954 ◽  
Vol 32 (8) ◽  
pp. 515-521 ◽  
Author(s):  
P. A. Fraser
Keyword(s):  
Internuclear Distance ◽  
Electronic Transition ◽  
Transition Probabilities ◽  
Transition Moment ◽  
Molecular Band ◽  
Vibrational Transition ◽  
Overlap Integrals ◽  
Electronic Transition Moment ◽  
Theoretical Results ◽  
Better Than

A method is described that will give the variation, as a function of internuclear distance, of the electronic transition moment governing intensities in diatomic molecular band systems. Reliable theoretical results and good experimental intensities are used conjointly to find this variation. Once smoothed, the trend may be replaced into the overlap integrals to give relative vibrational transition probabilities better than those given by the approximation ‘overlap integrals squared’, and presumably better than those deduced directly from experiment, since the latter are not smoothed. Limits on the application of the method are suggested; however many band systems fall within these limits.

The r-centroid concept revisited

2001 ◽  
Vol 79 (2-3) ◽  
pp. 611-622 ◽  
Author(s):  
R W Nicholls ◽  
M Amani ◽  
M Mandelman
Keyword(s):  
Electronic Transition ◽  
Transition Probability ◽  
Space Physics ◽  
Transition Moment ◽  
Internuclear Separation ◽  
Atmospheric Physics ◽  
Electronic Transition Moment ◽  
Intensity Measurements ◽  
Radiative Transitions ◽  
Recent Developments

The r-centroid concept, was proposed the in 1950s to permit factoring of the band strength integral Sυ',υ'' into the product of the Franck–Condon factor qυ',υ'', and of the square of the electronic transition moment Re (r), when taken at the r-centroid value of the internuclear separation, r = [Formula: see text]υ',υ'', which is the most likely value r at which the υ' « υ'' transition will occur. It has been much used since then in the interpretation of intensity measurements on many band systems of importance in astrophysics, atmospheric physics, space physics, and chemical physics to determine the variation of the electronic transition moment with internuclear separation, and thereby to derive band strengths, and other molecular transition probability parameters. It has been somewhat less used in recent years in the study of individual band systems, since the development of powerful computing facilities now allow for exact ab initio numerical studies to be made of individual molecules and their radiative transitions. Nevertheless the r-centroid concept, and some of its recent developments, provide much insight into the general systematics of diatomic molecular band systems and their spectra. This partly tutorial paper reviews the origins, properties, applications, and recent developments of the r-centroid concept. PACS No.: 33.70

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