Jet Propulsion Laboratory, California Institute of Technology 

Pasadena, California 91109

NRC AWARD - Duration 07.2002 - 07.2003

PROJECT:  Measurements of atomic oxygen cross section and high resolution spectrum of Electron-Excited SO₂ with  application for outer planet research.

Working Group: Joe Ajello, Grzegorz Osinski, Pralat Vatti Palle.

Project description:

The high resolution UV capabilities (l/Dl=10⁵) of the Hubble Space Telescope

(HST) equipped with the space telescope imaging spectrograph (STIS)

 reflects a need for high resolution laboratory UV spectral data base for

comparison with observation. For the purpose of interpreting the

astronomical observations of Io by HST the electron-excited UV spectrum

of SO₂ gas has been studied from 80-170 nm at medium (l/Dl~10³)

 and high resolution (l/Dl~5 x 10⁴) .

The spectrum consists entirely of  SI,II and OI, II multiplets.

From a measurement of the medium resolution spectrum at 0.15 nm FWHM

we are able to provide new detail in the 200 eV emission cross sections

for all the UV features. We have measured high resolution emission spectra

of the fine structure lines of the atomic multiplets at 125.5 nm from SII,

at 130.3 nm from OI, 142.9nm and 147.9nm from SI. We compare the optically  thin laboratory spectrum of the atomic multiplet at 147.9nm with

the model spectrum of electron excitation of atomic sulfur. In addition,

we compare a HST STIS observation of Io with the G140M grating

(FWHM~0.05nm) at 147.9 nm with the laboratory spectrum after

transmission through a layer of atomic S. The Doppler line profiles

of individual fine structure lines of atomic sulfur and oxygen were used

to ascertain the kinetic energy distribution from dissociative excitation

at 30 and 100 eV. We find the kinetic energy distribution of the oxygen

and sulfur  atoms to be in the range of 2eV to 3 eV at 100 eV

and we place an upper limit on the kinetic energy of sulfur and oxygen

atoms as <1 eV at 30 eV. We provide the first measurement

of the OI 135.6 absolute excitation function and the estimate

of the cross section ratio OI 135.6nm/130.4 nm as a function of energy.

We establish the absolute cross section of OI (130.4 nm)

as 2.3 x 10^-18 cm² at 100 eV and the estimated cross section of

OI (135.6 nm) as 2.1 x 10^-18 cm² at 100 eV.

More information you can find at:

COCOMO PROJECT

Kaiserslautern University, Germany

Duration: 11.2001 - 02.2002 as a visitor

Project description:

The Ne* apparatus is a linear setup which is about 4m long (figure above).

Beginning from the right we see the metastable source. Basically it's a

cold-cathode discharge which can either be cooled by water or

liquid nitrogen to control the mean velocity in the range

between 500m/s and 850m/s. The operation of the source can be monitored

 with a simple Faraday cup. The first laser interaction zone realizes

a 2D-polarization gradient cooling for beam brightening. In fact this cooling

 stage enhances the signal on axis by a factor of more than 20!

Two apertures collimate the atomic beam tightly.

The apertures can be exchanged without opening the machine.

If small Ne*-beam velocities are needed we use the Zeeman slowing

 technique to achieve atoms with a velocity of about 100m/s.

More information:

http://www.physik.uni-kl.de/bergmann/CoCoMoNetwork/home.html

Measurements of Cadmium atom parameters

in excited state ³P₁

_{Experimental setup}

_THEORY

S(B)=A Ä f(B) - measurement signal

A = a₁B +a₂ B + a₃ - apparaturs function

B_i = (B₀ + i DB) w- changing magnetic field

i = 1,2... n

f(B) = CS₁₂/2G + CS₁₃G / (G + w ) + CS₂₀G / (2G + 8w )

w = 2P m g B / h - Larmor frequency

RESULTS

_{Experimental observed signal}

_{Computer simulations with chaotic oscilations origin.}

_{Observed experimental signal in two-dimensions parametric  space}

_{has taken a instability picture of places for different parameters.}

_{It is better seems for Hanle effects signals:}

_{All space parameters for non-physical adaptive effects have taken interesting visibility shape, maybe with fractal structury expecially on a border :}

More information you may find in:G.Osinski, S.Legowski  ”Chaotic properties of optical double resonance and level crossing  signals from (5s5p)3P1 excited states of natural abundance of Cd  atoms”.

 Proc VI ECAMP  Siena p.672.7

PROJECT WAS SUPPORTED BY KBN GRANT   2 PO3B 111 14