Folded Optical Delay Lines

Herriott, D. R.; Schulte, Harry J.

doi:10.1364/ao.4.000883

Cited by 477 publications

(192 citation statements)

References 4 publications

Supporting

Mentioning

190

Contrasting

Unclassified

Order By: Relevance

“…Terahertz radiation generated through the first-order mixing of tunable microwave radiation with the output of a fixed frequency far-infrared (FIR) molecular gas laser was multipassed through the expansion 18-20 times in a Herriot cell configuration. 39 For the lower frequency (D 2 O) 5 high band density arising from a single species is quite rare and has interesting implications for the torsional energy manifold that will be discussed below. Transient absorption signals were then measured using a variable-field Putley-mode (VFP) photoconducting InSb detector (Advanced Kinetics).…”

Section: Methodsmentioning

confidence: 99%

Water Pentamer: Characterization of the Torsional-Puckering Manifold by Terahertz VRT Spectroscopy

et al. 2005

View full text Add to dashboard Cite

We present the measurement and analysis of five new (D 2 O) 5 bands via vibration-rotation-tunneling (VRT) spectroscopy as well as a preliminary description of a second (H 2 O) 5 band. The vibrationally averaged rotational constants of all five fitted bands agree well with those from the two previously observed (D 2 O) 5 bands and confirm that the pentamer averages to a symmetric, quasi-planar structure on the time scale of our experiment. While the spectrum of the first two bands, located at 50.7 cm -1 (1.52 THz) and 27.3 cm -1 (0.82 THz) are indicative of unperturbed oblate rotors, the three remaining (D 2 O) 5 bands centered at 47.7 cm -1 (1.43 THz), 45.4 cm -1 (1.36 THz), and 45.0 cm -1 (1.35 THz) are severely perturbed by first-order Coriolis coupling. This represents the first observation of this perturbation in the perdeuterated water pentamer, as well as the first observation of transitions between degenerate states of the torsional-puckering manifold. Unlike transitions from the (H 2 O) 5 band observed by Brown et al. at 89.0 cm -1 and the 103.8 cm -1 band that we report here, none of the individual rovibrational transitions of any of the five (D 2 O) 5 bands demonstrate spectral splittings due to bifurcation tunneling. We conclude, through careful analysis of these water pentamer bands, that at least three torsional-puckering manifolds have been probed and that the lowest-energy manifold is highly compacted. A plausible water pentamer torsional-puckering correlation diagram is proposed, though additional experimental data are required to unambiguously establish the energies of the torsional-puckering levels.

show abstract

Section: Methodsmentioning

confidence: 99%

Water Pentamer: Characterization of the Torsional-Puckering Manifold by Terahertz VRT Spectroscopy

et al. 2005

View full text Add to dashboard Cite

show abstract

“…Conventional multipass cells separate the individual reflections spatially with each reflection occurring on a different spot of the mirror (Herriott and Schulte 1965;White 1976). The laser beam is extracted after a given 31 number of roundtrips, as limited by the available mirror area.…”

Section: Introductionmentioning

confidence: 99%

Cavity Ring-Down and Cavity-Enhanced Detection Techniques for the Measurement of Aerosol Extinction

Moosmüller

Varma

Arnott

2005

Aerosol Science and Technology

101

View full text Add to dashboard Cite

An instrument employing cavity ring-down (CRD) and cavityenhanced detection (CED) for the local measurement of aerosol extinction is described and demonstrated. CRD measures the lifetime of photons in a high-quality optical cavity and thereby determines the sum of sample extinction between the cavity mirrors and that due to mirror losses. CRD systems can be calibrated with a single gas for the determination of extinction. A green laser emitting subnanosecond pulses is used as a light source, facilitating measurements free from optical interference in the cavity. The addition of a low-frequency chopper allows for the determination of extinction coefficients with simple linear fitting procedures and also facilitates CED measurements by providing laser power modulation for phase-sensitive detection. CED measures the average power transmitted by the optical cavity. After calibration with two gases, CED allows for the independent measurement of extinction with very high dynamic range and for an independent comparison with CRD measurements, thereby increasing confidence in the measurements.

show abstract

“…As medidas de concentração de CO 2 foram obtidas usando o instrumento "Tunable Diode Laser Spectrometer" (TDLS), cuja mangueira de sucção da amostra estava instalada a 4,5 m do solo, constituído por uma fonte de Laser "Diode" e uma célula de Herriott (Herriott & Schulte, 1965), que tem a função de garantir a velocidade de troca dos gases por meio de uma série de reflexões internas com utilização de espelhos. O princípio de funcionamento consiste no bombeamento da amostra de gás para o interior da célula de Herriott onde, a concentração do gásé mensurada através da absorçãoótica do raio laser.…”

Section: Metodologiaunclassified

Estudo da concentração do CO2 atmosférico em área de pastagem na região amazônica

Júnior¹,

Moura

Meixner

et al. 2004

Rev. Bras. Geof.

View full text Add to dashboard Cite

ABSTRACT. Carbon dioxide (CO 2 ) mixing ratios were continuously measured at a pasture site (Fazenda Nossa Senhora Aparecida) near Ouro Preto D'Oeste/RO during the period 15 April to 21 May 1999. This period corresponds to the transition between the wet to the dry season in this region. Photosynthesis by the vegetation of the pasture is the main sink for atmospheric CO 2 during daylight. During nighttime soil and plant respiration are a source for atmospheric CO 2 . Our results show a marked diurnal cycle of mean CO 2 mixing ratios. Mean mixing ratios above 500 ppmv are reached between 23:00 and 6:00 local time with a maximum of 533 ± 106 ppmv around 02:00 Values stay well below 400 ppmv between 9:00 and 17:00 and reach a minimum of 367 ± 8 ppmv around 15:00. Individual measurements performed during nights with low wind speeds especially show elevated CO 2 mixing ratios which might reach up to 800 ppmv.Keywords: CO 2 concentration, pasture, Amazonia.RESUMO. Medidas de concentração de dióxido de carbono (CO 2 ) foram realizadas em umaárea de pastagem no município de Ouro Preto do Oeste/RO (Fazenda Nossa Senhora Aparecida), no período de 15/04 -21/05/1999, período característico na região como sendo de transição entre a estação chuvosa para a seca. O período diurnoé o principal responsável pelo consumo de CO 2 devidoà realização da fotossíntese pelas plantas, enquanto no período noturno a respiração das plantas e dos microorganismos vivos responsáveis pela decomposição da matéria morta, liberam CO 2 para atmosfera. As concentrações de CO 2 tiveram valores acima de 500 ppmv entre 23:00 e 06:00 horas com um máximo de 533 ±106 ppmv aproximadamenteàs 02:00 horas, como também apresentaram valores mínimos abaixo de 400 ppmv entre 9:00 e 17:00 horas com mínimo de 367 ± 8 ppmv aproximadamenteàs 15:00 horas. Foram feitas várias comparações entre a concentração de CO 2 e algumas variáveis meteorológicas na busca de explicações para o ciclo diário da concentração de CO 2 , onde existe uma relação entre e a baixa velocidade do vento noturno e a concentração de CO 2 que alcança valores superiores a 800 ppmv.Palavras-chave: Concentração de CO 2 atmosférico, pastagem, Amazônia.

show abstract

Folded Optical Delay Lines

Cited by 477 publications

References 4 publications

Water Pentamer: Characterization of the Torsional-Puckering Manifold by Terahertz VRT Spectroscopy

Water Pentamer: Characterization of the Torsional-Puckering Manifold by Terahertz VRT Spectroscopy

Cavity Ring-Down and Cavity-Enhanced Detection Techniques for the Measurement of Aerosol Extinction

Estudo da concentração do CO2 atmosférico em área de pastagem na região amazônica

Contact Info

Product

Resources

About