Abstract

... Physical and Theoretical Chemistry Laboratory, Oxford University, Oxford OX1 3QZ, United Kingdom; and T. C. STEIMLE, Dept. of Chemistry and Biochemistry, Arizona State Univ., Tempe, AZ 85287. The pure rotational spectrum of CoF (X ) has been recorded in the frequency range 270-650 GHz - the fi ...

... Physical and Theoretical Chemistry Laboratory, Oxford University, Oxford OX1 3QZ, United Kingdom; and T. C. STEIMLE, Dept. of Chemistry and Biochemistry, Arizona State Univ., Tempe, AZ 85287. The pure rotational spectrum of CoF (X ) has been recorded in the frequency range 270-650 GHz - the fi ...

Abstract

... The sub-millimeter wave spectrum of the CoS radical has been observed in the frequency range 350-540 GHz using direct absorption techniques. This work is the first spectroscopic study of this molecule. Cobalt vapor was reacted with CS to produce CoS. Rotational transitions from three spin-componen ...

... The sub-millimeter wave spectrum of the CoS radical has been observed in the frequency range 350-540 GHz using direct absorption techniques. This work is the first spectroscopic study of this molecule. Cobalt vapor was reacted with CS to produce CoS. Rotational transitions from three spin-componen ...

MOLECULAR SPECTROSCOPY

... STORED WITH IN THE MOLECULE IN THE FORM OF : •(1) TRANSLATIONAL MOTION OF THE MOLECULE. •(2) INTERNAL MOVEMENT OF THE ATOMS OF THE MOLECULE, i.e. ROTATIONAL MOTION AND VIBRATIONAL MOTION. THERE ARE THREE TRANSLATIONAL DEGREE OF FREEDOM.THE REMAINING (3N-3) CO-ORDINATES REPRESENT THE INTERNAL DEGREE ...

... STORED WITH IN THE MOLECULE IN THE FORM OF : •(1) TRANSLATIONAL MOTION OF THE MOLECULE. •(2) INTERNAL MOVEMENT OF THE ATOMS OF THE MOLECULE, i.e. ROTATIONAL MOTION AND VIBRATIONAL MOTION. THERE ARE THREE TRANSLATIONAL DEGREE OF FREEDOM.THE REMAINING (3N-3) CO-ORDINATES REPRESENT THE INTERNAL DEGREE ...

slides introducing IR/Raman of proteins

... If molecule is centrosymmetric, no overlap of IR and Raman ...

... If molecule is centrosymmetric, no overlap of IR and Raman ...

Newton*s 2nd Law for Rotation, Angular Momentum

... • Angular momentum is “the product of a rotating object’s moment of inertia and angular speed about the same axis – Symbol: L , Unit: kg m2 / s –L=Iω – angular momentum = moment of inertia x angular speed ...

... • Angular momentum is “the product of a rotating object’s moment of inertia and angular speed about the same axis – Symbol: L , Unit: kg m2 / s –L=Iω – angular momentum = moment of inertia x angular speed ...

File

... When weight is the force causing torque, the center of gravity will be the geometric center for objects with symmetrical shaped and weight distributed uniformly. Here τ = ...

... When weight is the force causing torque, the center of gravity will be the geometric center for objects with symmetrical shaped and weight distributed uniformly. Here τ = ...

Rotational spectroscopy is concerned with the measurement of the energies of transitions between quantized rotational states of molecules in the gas phase. The spectra of polar molecules can be measured in absorption or emission by microwave spectroscopy or by far infrared spectroscopy. The rotational spectra of non-polar molecules cannot be observed by those methods, but can be observed and measured by Raman spectroscopy. Rotational spectroscopy is sometimes referred to as pure rotational spectroscopy to distinguish it from rotational-vibrational spectroscopy where changes in rotational energy occur together with changes in vibrational energy, and also from ro-vibronic spectroscopy (or just vibronic spectroscopy) where rotational, vibrational and electronic energy changes occur simultaneously.For rotational spectroscopy, molecules are classified according to symmetry into spherical top, linear and symmetric top; analytical expressions can be derived for the rotational energy terms of these molecules. Analytical expressions can be derived for the fourth category, asymmetric top, for rotational levels up to J=3, but higher energy levels need to be determined using numerical methods. The rotational energies are derived theoretically by considering the molecules to be rigid rotors and then applying extra terms to account for centrifugal distortion, fine structure, hyperfine structure and Coriolis coupling. Fitting the spectra to the theoretical expressions gives numerical values of the angular moments of inertia from which very precise values of molecular bond lengths and angles can be derived in favorable cases. In the presence of an electrostatic field there is Stark splitting which allows molecular electric dipole moments to be determined.An important application of rotational spectroscopy is in exploration of the chemical composition of the interstellar medium using radio telescopes.