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"A spectrometer application of time resolved method spectroscopy has been used in many times of experiment on physical of atomic, molecule and ionized plasma behavior. This paper is completed to make experimental work easier in reading and processing of datum. Using PC and interfaces can make signal convert to digital signals and it can save for long time in a very popular magnetic media. So, we can recall specific signal datum to re analyze or compare with new datum. Beside that, the spectrum of any saved datum can be printed many times.This half automatic spectrometer consists of:- Delay and Gating time,- Sample and Hold.- Analog to Digital Conversion ( ADC ).This design consists some modules of software that have been written in C language, and have compiled by a Borlan C compiler."

"Almost all of the breakthroughs in understanding the atmosphere have been initiated by field observations, using a range of instrumental techniques. Developing or deploying instruments to make further observations demands a thorough understanding of the chemical and spectroscopic principles on which such measurements depend. Written as an authoritative guide to the techniques of instrumental measurement for the atmospheric scientist, research student or undergraduate, Analytical Techniques for Atmospheric Measurement focuses on the instruments used to make real time measurements of atmospheric gas and aerosol composition. Topics covered include how they work, their strengths and weaknesses for a particular task, the platforms on which they have been deployed and how they are calibrated. It explains the fundamental principles upon which the instrumental techniques are based (i.e. what property of a molecule can be exploited to enable its detection), what limits instrumental sensitivity and accuracy, and the information that can be gained from their use--Publisher's blurb."

"ABSTRAKA compact, simple and low-cost transversely excited atmospheric (TEA) pressure ultraviolet nitrogen laser {337 nm) has been designed and constructed employing the conventional Blumlein circuit. The measured energy of the output pulse of 337 nm is around 80 -J at 25 kV of charging voltage and l atm operating gas pressure. The beam divergence is found to be 7.7 mrad horizontally and 1.5 mrad vertically. The energy output decreases slightly with increasing gas pressure and gas flow rate, while the beam divergence is relatively stable with respect to the same operating parameters."

"ABSTRACTThe construction and excitation circuit of carbon dioxide laser 616 mm long is described. The dependence of the pulse emission energy on the energy supplied to the discharge, the pressure and composhdon gaseous mixture is presented. The emission energy is 1-2 Joules. The emission pulse isexpected to cover range from 100 ns - 200 ns."

"Rasmus Brogaard's thesis digs into the fundamental issue of how the shape of a molecule relates to its photochemical reactivity. This relation is drastically different from that of ground-state chemistry, since lifetimes of excited states are often comparable to or even shorter than the time scales of conformational changes. Combining theoretical and experimental efforts in femto-second time-resolved photoionization Rasmus Brogaard finds that a requirement for an efficient photochemical reaction is the prearrangement of the constituents in a reactive conformation. Furthermore, he is able to show that by exploiting a strong ionic interaction between two chromophores, a coherent molecular motion can be induced and probed in real-time. This way of using bichromophoric interactions provides a promising strategy for future research on conformational dynamics."

"ABSTRAKTujuan dari eksperimen yang dilakukan adalah untuk menyelidiki hal-hal yang berkaitan dengan pembentukan plasma, yakni zat yang tersusun dari muatan-muatan listrik bebas berupa ion-ion positif dan elektron elektron negatif yang jumlahnya nyaris sama.Plasma yang digunakan dalam eksperimen terbentuk dari udara laboratorium yang di iradiasi dengan berkas laser energi tinggi ( IJ - 2J ) dalam sebuah chamber yang dilengkapi dengan suatu rangkaian listrik DC.Dengan memberikan beda tegangan tertentu antara dua elektrode yang berada dalam chamber, maka elektron-elektron dari plasma yang berada diantara kedua elektrode tersebut akan ditarik oleh elektrode positif dan menimbulkan arus listrik pada resistor yang ada dalam rangkaian. Besar arus listrik yang mengalir ini dapat ditentukan harganya dengan cara mengukur besar tegangan pada resistor menggunakan cathode ray oscilloscope.Chamber yang merupakan kotak tertutup berisi plasma yang diamati, dilengkapi dengan pengukur tekanan, dan di hubungkan ke sebuah pompa vakum.Dengan memvariasi besar tekanan udara dalam chamber, jarak antar elektrode, beda tegangan antara elektrode, maupun besar energi laser, dapat diperoleh harga besaran-besaran fisis yang diselidiki, juga korelasi-korelasi antara suatu besaran fists, dengan besaran fists lainnya.

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ABSTRACT

An investigation has been conducted on the formation of plasma generated by focusing an intense Laser radiation.

A high voltage from DC source is used to trigger electrical breakdown between two electrodes which an air of laboratory will be investigated.

The electrical breakdown caused by laser radiation observed by measuring the voltage of pick up resistor in the electrical circuit. The value of electric current flows in resistor can be calculated from the value of voltage, it expresses the amount of electrons flow from plasma. By variating air pressure in the chamber, distance between two electrodes, potential difference between two electrodes, and laser energy, we can find correlations between: air pressure versus breakdown probability, air pressure versus electron number density, Laser energy versus electron number density, electric field per pressure versus electron drift velocity, etc."

"Iradiasi laser Nd-YAG dengan energi 26 mJ dan lebar pulsa 8 ns difokuskan pads target zinc dilingkungan udara bertekanan 1 atm. Untuk mengetahui apakah laser plasma yang dihasilkan mengikuti mekanisme gas breakdown atau mengikuti mekanisme gelombang kejut, laju propagasi muka emisi plasma dan gelombang kejut diukur secara bersamaan. Dari hasil pengukuran terlihat jelas bahwa plasma laser yang dibangkitkan mengikuti model gelombang kejut sferis seperti yang telah diturunkan oleh Sedov. Pada proses awal dari iradiasi laser, muka emisi plasma akan berimpit dengan gelombang kejut, menandakan plasma ada dalam tahapan proses eksitasi. Pada tahap akhir dari iradiasi laser, muka gelombang kejut akan meninggalkan muka emisi plasma dan dalam kondisi ini plasma berada dalam tahapan pendinginan. Lebih lanjut ditunjukkan dengan menaikan densitas daya pada permukaan target, waktu pada tahapan eksitasi akan bertambah besar."

"ABSTRAKTelah dilakukan penelitian efek penguapan selektif (selective vaporation) plasma gelombang kejut (shock wave plasma) yang dibangkitkan dengan memfokuskan iradiasi laser TEA CO2 (130 mJ, 100 ns) atau laser Nd-YAG (50mJ, 8ns) pada bahan kuningan yang memiliki kandungan Zn (seng) dan Cu (tembaga) dalam udara tekanan rendah (1 Torr). Efek penguapan selektif akan terjadi apabila rapat daya laser yang digunakan tidak terlalu tinggi dibandingkan dengan nilai ambang batas pembangkitan plasma. Hasil pengamatan menunjukkan bahwa intensitas emisi Cu jauh lebih rendah dibandingkan dengan intensitas emisi Zn. Juga telah diamati bahwa titik awal (rising point) emisi Cu tertinggal dibandingkan dengan titik awal emisi Zn sepanjang daerah pengembangan plasma. Dalam kasus iradiasi laser CC2, penguapan selektif lebih dominan, dan kecepatan propagasi atom-atom Cu sangat rendah dibandingkan dengan atom-atom Zn. Hal ini menunjukkan bahwa gelombang kejut adalah dibentuk dari kumpulan atom-atom Zn, sedangkan atom-atom Cu yang datang terlambat tidak mampu membangkitkan gelombang kejutnya sendiri. Dilain pihak atom-atom Cu tersebut di atas juga tertinggal jauh dari muka gelombang kejut yang terbentuk oleh atorn-atom Zn, mengakibatkan atom-atom Cu ini tidak akan pernah tereksitasi.

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ABSTRACT

TEA CO2 laser (130 mJ, 100 ns) and Nd-YAG laser (50 mJ, 8 ns) pulses were focused on brass samples under a reduced pressure of air at 1 Torr, and In and Cu emission characteristics were compared for the two cases. For the TEA CO2 laser the emission intensity of copper lines is extremely low, compared to zinc lines, indicating a serious selective-vaporization effect. By comparing the time-profile of the emission of In 1481.0 nm and Cu 1 327.4 nm near the surface, it was clearly shown that the gushing of Cu atoms occur later and continues for a long time with a rather low gushing speed, while In gushes faster at a high speed. Only In atoms form a shock front and Cu is left behind the shock-wave and does not undergo excitation. This type of selective vaporization takes place only when the power density of laser light is not high, compared to the threshold for plasma generation. The phenomenon of selective vaporization described in this paper also supports our laser-induced shock wave model."