7 research outputs found
Atmospheric Helium Capillary Dielectric Barrier Discharge for Soft Ionization: Determination of Atom Number Densities in the Lowest Excited and Metastable States
The populations of the lowest excited
helium states 2s <sup>3</sup>S<sub>1</sub>, 2s <sup>1</sup>S, 2p <sup>3</sup>P<sup>0</sup><sub>J</sub>, and 2p <sup>1</sup>P<sup>0</sup> created in an atmospheric
helium capillary dielectric barrier discharge were determined by means
of optical emission spectroscopy. The emitted intensities of 388,
501, 587, and 667 nm lines were measured side-on and end-on with respect
to the discharge axis. The comparison of optically thin side-on spectra
with end-on spectra, which exhibited the absorption effects in the
line kernels, enabled the determination of the average values of the
number densities <i>n</i><sub>1</sub> in the considered
He states along the plasma length <i>L</i>. The field of
the theoretical profiles for a series of the <i>n</i><sub>1</sub><i>L</i> parameters pertinent to the experimental
conditions was calculated for each line. By introducing the experimental
data into the field of calculated curves, <i>n</i><sub>1</sub><i>L</i> corresponding to the particular state could be
obtained. The measurements of the emission profiles were done as a
function of the discharge voltage in the range covering homogeneous
as well as filamentary DBD operation mode. Due to nonuniformity of
the excited atom density distribution along the plasma, the values
of <i>n</i><sub>1</sub> could be obtained only in the homogeneous
operation mode where the nonuniformity was small. The following maximum
values were found for the number densities in the investigated states: <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>3</sup>S<sub>1</sub>) = (2.9 ± 1.1) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>1</sup>S) = (1.4 ±
0.5) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>3</sup>P<sup>0</sup><sub>J</sub>) = (1.1 ± 0.4) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>1</sup>P<sup>0</sup>) = (4.2 ± 1.6) × 10<sup>12</sup> cm<sup>–3</sup>, and they represent the average populations along the plasma column
in the capillary
Atmospheric Helium Capillary Dielectric Barrier Discharge for Soft Ionization: Determination of Atom Number Densities in the Lowest Excited and Metastable States
The populations of the lowest excited
helium states 2s <sup>3</sup>S<sub>1</sub>, 2s <sup>1</sup>S, 2p <sup>3</sup>P<sup>0</sup><sub>J</sub>, and 2p <sup>1</sup>P<sup>0</sup> created in an atmospheric
helium capillary dielectric barrier discharge were determined by means
of optical emission spectroscopy. The emitted intensities of 388,
501, 587, and 667 nm lines were measured side-on and end-on with respect
to the discharge axis. The comparison of optically thin side-on spectra
with end-on spectra, which exhibited the absorption effects in the
line kernels, enabled the determination of the average values of the
number densities <i>n</i><sub>1</sub> in the considered
He states along the plasma length <i>L</i>. The field of
the theoretical profiles for a series of the <i>n</i><sub>1</sub><i>L</i> parameters pertinent to the experimental
conditions was calculated for each line. By introducing the experimental
data into the field of calculated curves, <i>n</i><sub>1</sub><i>L</i> corresponding to the particular state could be
obtained. The measurements of the emission profiles were done as a
function of the discharge voltage in the range covering homogeneous
as well as filamentary DBD operation mode. Due to nonuniformity of
the excited atom density distribution along the plasma, the values
of <i>n</i><sub>1</sub> could be obtained only in the homogeneous
operation mode where the nonuniformity was small. The following maximum
values were found for the number densities in the investigated states: <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>3</sup>S<sub>1</sub>) = (2.9 ± 1.1) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>1</sup>S) = (1.4 ±
0.5) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>3</sup>P<sup>0</sup><sub>J</sub>) = (1.1 ± 0.4) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>1</sup>P<sup>0</sup>) = (4.2 ± 1.6) × 10<sup>12</sup> cm<sup>–3</sup>, and they represent the average populations along the plasma column
in the capillary
Atmospheric Helium Capillary Dielectric Barrier Discharge for Soft Ionization: Determination of Atom Number Densities in the Lowest Excited and Metastable States
The populations of the lowest excited
helium states 2s <sup>3</sup>S<sub>1</sub>, 2s <sup>1</sup>S, 2p <sup>3</sup>P<sup>0</sup><sub>J</sub>, and 2p <sup>1</sup>P<sup>0</sup> created in an atmospheric
helium capillary dielectric barrier discharge were determined by means
of optical emission spectroscopy. The emitted intensities of 388,
501, 587, and 667 nm lines were measured side-on and end-on with respect
to the discharge axis. The comparison of optically thin side-on spectra
with end-on spectra, which exhibited the absorption effects in the
line kernels, enabled the determination of the average values of the
number densities <i>n</i><sub>1</sub> in the considered
He states along the plasma length <i>L</i>. The field of
the theoretical profiles for a series of the <i>n</i><sub>1</sub><i>L</i> parameters pertinent to the experimental
conditions was calculated for each line. By introducing the experimental
data into the field of calculated curves, <i>n</i><sub>1</sub><i>L</i> corresponding to the particular state could be
obtained. The measurements of the emission profiles were done as a
function of the discharge voltage in the range covering homogeneous
as well as filamentary DBD operation mode. Due to nonuniformity of
the excited atom density distribution along the plasma, the values
of <i>n</i><sub>1</sub> could be obtained only in the homogeneous
operation mode where the nonuniformity was small. The following maximum
values were found for the number densities in the investigated states: <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>3</sup>S<sub>1</sub>) = (2.9 ± 1.1) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>1</sup>S) = (1.4 ±
0.5) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>3</sup>P<sup>0</sup><sub>J</sub>) = (1.1 ± 0.4) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>1</sup>P<sup>0</sup>) = (4.2 ± 1.6) × 10<sup>12</sup> cm<sup>–3</sup>, and they represent the average populations along the plasma column
in the capillary
Atmospheric Helium Capillary Dielectric Barrier Discharge for Soft Ionization: Determination of Atom Number Densities in the Lowest Excited and Metastable States
The populations of the lowest excited
helium states 2s <sup>3</sup>S<sub>1</sub>, 2s <sup>1</sup>S, 2p <sup>3</sup>P<sup>0</sup><sub>J</sub>, and 2p <sup>1</sup>P<sup>0</sup> created in an atmospheric
helium capillary dielectric barrier discharge were determined by means
of optical emission spectroscopy. The emitted intensities of 388,
501, 587, and 667 nm lines were measured side-on and end-on with respect
to the discharge axis. The comparison of optically thin side-on spectra
with end-on spectra, which exhibited the absorption effects in the
line kernels, enabled the determination of the average values of the
number densities <i>n</i><sub>1</sub> in the considered
He states along the plasma length <i>L</i>. The field of
the theoretical profiles for a series of the <i>n</i><sub>1</sub><i>L</i> parameters pertinent to the experimental
conditions was calculated for each line. By introducing the experimental
data into the field of calculated curves, <i>n</i><sub>1</sub><i>L</i> corresponding to the particular state could be
obtained. The measurements of the emission profiles were done as a
function of the discharge voltage in the range covering homogeneous
as well as filamentary DBD operation mode. Due to nonuniformity of
the excited atom density distribution along the plasma, the values
of <i>n</i><sub>1</sub> could be obtained only in the homogeneous
operation mode where the nonuniformity was small. The following maximum
values were found for the number densities in the investigated states: <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>3</sup>S<sub>1</sub>) = (2.9 ± 1.1) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>1</sup>S) = (1.4 ±
0.5) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>3</sup>P<sup>0</sup><sub>J</sub>) = (1.1 ± 0.4) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>1</sup>P<sup>0</sup>) = (4.2 ± 1.6) × 10<sup>12</sup> cm<sup>–3</sup>, and they represent the average populations along the plasma column
in the capillary
Atmospheric Helium Capillary Dielectric Barrier Discharge for Soft Ionization: Determination of Atom Number Densities in the Lowest Excited and Metastable States
The populations of the lowest excited
helium states 2s <sup>3</sup>S<sub>1</sub>, 2s <sup>1</sup>S, 2p <sup>3</sup>P<sup>0</sup><sub>J</sub>, and 2p <sup>1</sup>P<sup>0</sup> created in an atmospheric
helium capillary dielectric barrier discharge were determined by means
of optical emission spectroscopy. The emitted intensities of 388,
501, 587, and 667 nm lines were measured side-on and end-on with respect
to the discharge axis. The comparison of optically thin side-on spectra
with end-on spectra, which exhibited the absorption effects in the
line kernels, enabled the determination of the average values of the
number densities <i>n</i><sub>1</sub> in the considered
He states along the plasma length <i>L</i>. The field of
the theoretical profiles for a series of the <i>n</i><sub>1</sub><i>L</i> parameters pertinent to the experimental
conditions was calculated for each line. By introducing the experimental
data into the field of calculated curves, <i>n</i><sub>1</sub><i>L</i> corresponding to the particular state could be
obtained. The measurements of the emission profiles were done as a
function of the discharge voltage in the range covering homogeneous
as well as filamentary DBD operation mode. Due to nonuniformity of
the excited atom density distribution along the plasma, the values
of <i>n</i><sub>1</sub> could be obtained only in the homogeneous
operation mode where the nonuniformity was small. The following maximum
values were found for the number densities in the investigated states: <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>3</sup>S<sub>1</sub>) = (2.9 ± 1.1) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>1</sup>S) = (1.4 ±
0.5) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>3</sup>P<sup>0</sup><sub>J</sub>) = (1.1 ± 0.4) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>1</sup>P<sup>0</sup>) = (4.2 ± 1.6) × 10<sup>12</sup> cm<sup>–3</sup>, and they represent the average populations along the plasma column
in the capillary
Atmospheric Helium Capillary Dielectric Barrier Discharge for Soft Ionization: Determination of Atom Number Densities in the Lowest Excited and Metastable States
The populations of the lowest excited
helium states 2s <sup>3</sup>S<sub>1</sub>, 2s <sup>1</sup>S, 2p <sup>3</sup>P<sup>0</sup><sub>J</sub>, and 2p <sup>1</sup>P<sup>0</sup> created in an atmospheric
helium capillary dielectric barrier discharge were determined by means
of optical emission spectroscopy. The emitted intensities of 388,
501, 587, and 667 nm lines were measured side-on and end-on with respect
to the discharge axis. The comparison of optically thin side-on spectra
with end-on spectra, which exhibited the absorption effects in the
line kernels, enabled the determination of the average values of the
number densities <i>n</i><sub>1</sub> in the considered
He states along the plasma length <i>L</i>. The field of
the theoretical profiles for a series of the <i>n</i><sub>1</sub><i>L</i> parameters pertinent to the experimental
conditions was calculated for each line. By introducing the experimental
data into the field of calculated curves, <i>n</i><sub>1</sub><i>L</i> corresponding to the particular state could be
obtained. The measurements of the emission profiles were done as a
function of the discharge voltage in the range covering homogeneous
as well as filamentary DBD operation mode. Due to nonuniformity of
the excited atom density distribution along the plasma, the values
of <i>n</i><sub>1</sub> could be obtained only in the homogeneous
operation mode where the nonuniformity was small. The following maximum
values were found for the number densities in the investigated states: <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>3</sup>S<sub>1</sub>) = (2.9 ± 1.1) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2s <sup>1</sup>S) = (1.4 ±
0.5) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>3</sup>P<sup>0</sup><sub>J</sub>) = (1.1 ± 0.4) × 10<sup>13</sup> cm<sup>–3</sup>, <i>n</i><sub>1</sub><sup>av</sup> (2p <sup>1</sup>P<sup>0</sup>) = (4.2 ± 1.6) × 10<sup>12</sup> cm<sup>–3</sup>, and they represent the average populations along the plasma column
in the capillary
Soft Argon–Propane Dielectric Barrier Discharge Ionization
Dielectric
barrier discharges (DBDs) have been used as soft ionization
sources (DBDI) for organic mass spectrometry (DBDI-MS) for approximately
ten years. Helium-based DBDI is often used because of its good ionization
efficiency, low ignition voltage, and homogeneous plasma conditions.
Argon needs much higher ignition voltages than helium when the same
discharge geometry is used. A filamentary plasma, which is not suitable
for soft ionization, may be produced instead of a homogeneous plasma.
This difference results in N<sub>2</sub>, present in helium and argon
as an impurity, being Penning-ionized by helium but not by metastable
argon atoms. In this study, a mixture of argon and propane (C<sub>3</sub>H<sub>8</sub>) was used as an ignition aid to decrease the
ignition and working voltages, because propane can be Penning-ionized
by argon metastables. This approach leads to homogeneous argon-based
DBDI. Furthermore, operating DBDI in an open environment assumes that
many uncharged analyte molecules do not interact with the reactant
ions. To overcome this disadvantage, we present a novel approach,
where the analyte is introduced in an enclosed system through the
discharge capillary itself. This nonambient DBDI-MS arrangement is
presented and characterized and could advance the novel connection
of DBDI with analytical separation techniques such as gas chromatography
(GC) and high-pressure liquid chromatography (HPLC) in the near future